You (the consultant) sets the rate you get paid. Toptal adds a secret margin on top of that which is what the client pays.

I haven't done Toptal in a while, but my rate was always higher than that. I got pushback from from Toptal's internal recruiters whenever I asked to increase my rate and a few of their clients did turn me down due to the rate. But I never backed down and it never took more than a few weeks between starting applying to jobs on Toptal to signing a contract.

I wouldn't want to depend on Toptal for my income. But it's great as a way to fill in between other engagements if you're firm with your rate and the kind of work you want.