That's not how exchanges or prediction markets work. They need - and welcome - sharp action.
Some bookmakers are marketing companies that will kill unprofitable accounts, but not all of them. It does not take a lot of work and research to work out who is who if you want to take this seriously, or how to make sure your account stays under the radar long enough, or even how to get around those mechanisms - some of those techniques may ultimately be considered fraud, however.
And if you don't want to take it seriously, what are you doing throwing huge wads of cash at it?
Some bookmakers are marketing companies that will kill unprofitable accounts, but not all of them. It does not take a lot of work and research to work out who is who if you want to take this seriously, or how to make sure your account stays under the radar long enough, or even how to get around those mechanisms - some of those techniques may ultimately be considered fraud, however.
And if you don't want to take it seriously, what are you doing throwing huge wads of cash at it?