That's very true for most of them.
They even have their own foundations just to avoid the preying eyes of the Tax Collectors.
And with Beckham, I can say that maybe there's some truth with the leaked emails, though they were saying that those were faked. If those were tampered, the amount of money that the hackers want should not be that enormous & now it's like a terminating point for all his endorsements.
In the end, we don't know him in real person. So who are we to judge?