The examples you gave may have been bad decisions (in hindsight), but they were not mistakes. Those decisions may have had unforeseen consequences and had results different than those you expected, but that does not make them mistakes. It simply makes them bad decisions. For example - You didn't think you were getting a Business Degree, only to find out that you had mistakenly taken classes that qualified you for a Fine Arts, not Business, degree. You intentionally pursued a Fine Arts degree, but it turned out in ways you did not intend.
That may sound like I am being an a-hole; but actually that is not my intention. People are ever increasingly referring to intentional decisions as mistakes, but - by definition - they are not. Many - and I am not suggesting this applies to you - re-label things as a mistake as a way of reducing their personal culpability for the negative results and outcome. For example, I have heard people say things like "having an affair was the worst mistake of my life". I seriously doubt that they found themselves naked and mounting another person as a result of a mistake. No, I am sure that the process to get naked and mount another person was a very intentional decision (or series of decisions), although it may have been something they later regretted (probably after their spouse found out, filed for divorce and they had to pay alimony). Radio host Dennis Prager frequently says "the Government shutting down the economy due to COVID-19 was one of the biggest mistakes of all time". But the Government intentionally shut down the economy; their doing so was not a mistake (and in this example, I do not believe those who made the decisions to do so were surprised by the outcome - the results and outcomes were EXACTLY what they expected). The Government shutting down the economy due to COVID-19 was a bad decision.
Many years ago, I intentionally asked a woman (who later proved to be a horrible person) to marry me. That was not a mistake, but time proved that it was an awful decision with many unforeseen consequences and was something I regretted in the strongest way. After her 2nd affair, I divorced her. That, too, was an intentional decision (a very good one). But, there were no mistakes.
I do not mean any disrespect by posting this reply. If I came across as a jerk, PM me and I will delete it.