The Bill Gates family believes in trying to impact a little change in the world, no matter how little. You can't change everything, but the little you can will greatly impact someone's life. This is their belief, which is why they plan to give away most of their fortune as long as their children won't have to suffer and are settled, even as he said most of his children won't end up being billionaires.
Bill gates stopped accumulating wealth years ago, all his money is from Microsoft times, it's no different from the wealth owners of crypto would get over time, I am not doing a thing yet I saw my stash gain 1000% in value over the last 5-6 years, I'm not accumulating wealth I'm just enjoying a well placed investment.
It could also be said to be a regenerational wealth; you have worked smart to invest in something which has been given to you that wealth which you are enjoying. Your money and your smart investment have given you more wealth; it could also be said to be a wealth accumulation. On the other hand, as long as your money is increasing.