I do not believe the Web3 market can be computed in a number of $s.

In one sense, the Web3 market is larger than whole world market currently.
In another sense, you won't be able to say you have 3% of the Web3 market.

The thing is, Web3 will bring to the table, the undeveloped world.
And exchanges will quickly stop being in dollars.
And will probably be a like a giant barter thingy... with bitcoin as the glue... or maybe just the measuring stick.

So, probably the Web3 market will be 1 million BTC