poorstudent There's a limit in the smart contract for how much can be withdrawn in 1 day, it's in several % of total supply. This is generally a stopgap to prevent catastrophic failures (ie some sort of hack). Expectation is it will never need to be used but we don't live in a perfect world.
Separately, governors of the Morpher Protocol can in theory freeze ERC20 tokens and revert - again in case of a hack. We're adding a staking model so that over time community can take up admin role and decentralize.
Otherwise as long as the blockchain bridges are up you can always withdraw. There's no such thing as liquidity when it comes to the existence of the ERC20 tokens. There are liquidity limits in ETH on Uniswap and Gate.io, so if you sell a ton of MPH the price falls. Here's what we mention on that in MPH FAQ
Selling pressure on crypto exchanges does not change the utility of MPH. The entire Morpher protocol works at any token price. At lower prices, trading on Morpher actually becomes cheaper and more efficient than any traditional brokerage platform.
You might also want to take a look at Hedging Mechanisms.