For a few thousand bucks, they're not going to make an example of you. It's not worth it to them. If you're cashing in 6 figures to buy luxury cars, they might, I agree. You go after the big fish, not the small fries.
e.g. https://www.propublica.org/article/irs-sorry-but-its-just-ea...
Your casual bitcoin spender is not going to be like that at all. Their under reported transactions will be difficult to even find. If you do find them, their true cost basis will be difficult to determine.