No, they aren't, because the price of BTC is growing exponentially without necessarily having dollar deposits grow at the same time. Here's a worked example.
In a closed system:
Day 1: $1 buys 1000 Marmotcoin
Day 2: $1000 buys 1 Marmotcoin
Day 3: 1000 Marmotcoin attempts to sell for $1,000,000
That's what the initial phases of a liquidity shock will look like. I can almost guarantee you that retail operations all have bank liquidity facilities to deal with sudden upswings in withdrawal demand, otherwise they have to commit house money to cover it.
In a closed system:
Day 1: $1 buys 1000 Marmotcoin
Day 2: $1000 buys 1 Marmotcoin
Day 3: 1000 Marmotcoin attempts to sell for $1,000,000
That's what the initial phases of a liquidity shock will look like. I can almost guarantee you that retail operations all have bank liquidity facilities to deal with sudden upswings in withdrawal demand, otherwise they have to commit house money to cover it.