You might say, no, Musk and Bezos are worth 50% (or ~60 billion) more. On paper yes, but that's not a great metric. When I think of wealth, I think of what you can reasonably acquire.
If you multiply Musk's shares in Tesla times the current share price, sure you get 180 billion. But if he tried to sell a large number those shares, they'd plummet in value as he was selling them. Without Musk, I'd be surprised if Tesla is worth 20% of its current valuation. To a lesser extent, this is true of Bezos too, although Amazon without him is still a very valuable company.
On the other hand, Bill Gates owns 1.6% of Microsoft, which I believe is his biggest holding, followed by Berkshire Hathaway stock. I'd bet he can sell both of those holdings completely without a huge hit to either stock price (but definitely some hit). Same with his farmland and other alternative assets. On top of that, having already sold his Microsoft shares, he's not subject to as much capital gains tax as Bezos or Musk, each of whom pretty much owe 20% of their total net worth the second they want to sell.
So on paper, Musk and Bezos are wealthier, but if all of them decided to Scrooge McDuck it and put all their money into a gold filled vault tomorrow, Bill Gates' vault would be the fullest.
EDIT: typo above... Originally said that Musk owns 180 bn in Amazon stock :)