Since they have bigger incomes, the IRS looks at them harder. If you make $30k and lie on your taxes to save $100, you could probably get away with it (don't test your luck though).

But if your income is $10 million, they are going through your shit with a fine tooth comb.

Also, they get their money in big lump sums and taxes are not automatically taken out.
When someone hands you a big check, you're not thinking about paying taxes. You're thinking about what you can buy.

Finally, shady financial advisers.