One brings a korban for one of two reasons: either because one wants to or because one has to. One may offer a korban as a way of saying thank you for the blessings of life. Instead of, or perhaps in addition to inviting some friends over to celebrate, one transforms the feast into a seudat mitzvah by celebrating in Jerusalem, publicly offering thanksgiving to G-d and sharing their bounty with others.
At the other extreme, one brings a korban because one has violated a serious Torah prohibition. For those sins where willful violation brings the punishment of karet, excision, those who violate that prohibition accidentally must bring a korban chatat, a sin offering.
While a chatat is brought for an inadvertent sin, in rare circumstances one is obligated to bring a korban even for a willful violation of the law. The korban asham is brought when one swears under oath that one has not stolen money and later admits that they did, if one has made personal use of sanctified property meant for use in the Temple, or if one has relations with a maidservant.
And then we have the institution of an asham talui, literally a “hanging sin”. This korban is brought when one is uncertain as to whether one has violated an issur karet. Such would be the case if there were two pieces of meat before him, one containing shuman, permitted fats, and one containing chelev, forbidden fats, and one is unsure which one they ate. Being in doubt as to whether one has violated a prohibition that carries with it the penalty of karet, one must bring an asham talui.
In many ways, being in doubt as to whether one has sinned is worse than having knowingly sinned. For starters, if and when one finds out that they did actually eat chelev, they would have to bring a korban chatat. The asham talui is a stopgap measure that one brings while they wait to find out if they have in fact sinned.
Moreover, one can be sorry they did something wrong and properly do teshuva, but it is very difficult to do so if one is not even sure they have sinned. Humans are just not wired that way. Thus, the RaMaH (Orach Chaim, 603) rules that “a doubtful sin requires more [efforts at] teshuva than a sin knowingly violated, as one has greater regret when one knows they have done something wrong than when one does not know”. And without regret, teshuva is not possible. It is not only the stock market that detests uncertainty.
The RaMaH continues with, “For this reason, the sacrifice of an ashum talui must be more expensive than a korban chatat”, the former being a ram and the latter a sheep.
The last Mishna in masechet Yoma states that a chatat and asham vadai, the two types of korbanot brought for knowingly having sinned, atone. Conspicuously absent in any mention of an asham talui. This korban offers little atonement. Only when one actually finds out they have sinned is teshuva—and hence, atonement—fully possible.
“Rabbi Eliezer says a person may volunteer to bring an asham talui every day and any time he wants, and this is called the asham chasidim, the sin offering of the pious” (Keritot 25a). Can one ever be certain that they have not sinned? Ironically, those who would volunteer to bring an asham talui are those less likely to sin in the first place. The pious are pious because they worry lest they sin.
Yet however pious this may sound, it is likely a most dangerous approach, one that may in fact push people away from piety. “But the Sages say: One does not bring an asham talui, save for [an action] whose willful violation is karet and unwitting violation is a chatat.”
To be constantly bringing a korban because one may have sinned is for most people a recipe for disaster (and this, before we discuss what such an approach might cost). While one must examine one's ways looking for ways to improve, to view oneself as a potential sinner day in and day out is potentially devastating. Such a life is just not normal or healthy, and while it may work for the few Bava ben Butas of the world, it is the approach of the Sages that is the path to take.
 It is worth noting that originally, one was allowed to eat meat only in the context of bringing sacrifices. Only later did the Torah allow basar ta’avah, literally “meat of lust”, when one could eat meat whenever and wherever one pleased.
 While there are 36 such sins, a korban chatat is brought for only 31 of them. Brit milah and korban pesach are positive mitzvot, the only two the neglect of which makes one liable for karet, and acts of omission do not obligate one in a korban; rather, one should just do the mitzvah. Similarly, speech is not technically considered an action and thus, one who curses G-d need not bring a korban—though they (and those who curse their parents) may be liable for a death penalty. And entering the Temple or eating sacrificial meat while in a state of tumah, impurity, is atoned by bringing a korban oleh v’yored, not a korban chatat.
 Fascinatingly, if there are three pieces of meat, two of shuman and one of chelev, all authorities agree that one can choose two of three to eat—despite the fact that, statistically speaking, there is a 66.67% chance one will eat non-kosher food. The Shulchan Aruch (Yoreh Deah 109:1) quotes approvingly the view that one can eat all three provided one does not eat them at the same time. As we pick up each individual piece, chances are 66.67% that it is kosher, and Jewish law allows one to rely on rov, a majority.
 The Gemara explains "the reason one brings an asham talui although the sin is uncertain, is to afford protection [from suffering], because the Torah has compassion upon the lives of Israel" (Keritot 25a). The Gemara is quite clear that being spared from punishment and atonement are two separate matters.
 This is the only mention of Bava ben Buta in the entire Mishna. Generally speaking, extreme piety and outstanding Torah scholarship do not go hand in hand (the Chafetz Chaim being a notable exception) as each requires superhuman efforts in differing fields.