not that the OP has anything similar to this story.
My dad managed the financial side of my brother's business during the construction boom in the early 2000's. My brother ran a couple of crews doing framing for new builds. My dad, an interesting guy though I love him deeply, always thought he knew how to make a deal. He considered himself to be smart enough to manage anything, including taxes. Well with my brother's business he claimed a loss for a couple years in a row. He really thought he would "out-smart" the IRS. My brother was making pretty good money at the time and was supporting a blended family that was quite large. He had new vehicles (likely bought through the business). He wasn't very savvy when it came to taxes and he actually trusted my dad pretty much to handle it.
Well of course after a few years of claiming total losses (where his tax burden was nothing) the IRS came auditing. My Brother got hit with 100,000 or so in tax penalties. It happened right when the boom was ending and right as my brother was finding that his back pain was too much to handle. I don't know if he ever paid the money back tbh.
Moral of the story. Get an accountant if you don't want to do your own taxes.