Beckham has, apparently, a net worth of around $670 as of 2021 (can't be bothered to look at the ER). £8 million will make a small dent.
He's got contracts with various 'high end' manufacturers (or did have) like Tudor watches and Haig Club Whisky, which are probably quite lucrative, so he's not going to run short...
David did not inherit his wealth. He and his wife made it through sport and entertainment which we, the public, endorse) - and their own business ventures. If they pay their due taxes, I'm not going to condemn them, or how they spend their money.
It's a different world they live in though, that's for sure...