I'm having a difficult time in trusting any of these online exchanges, what is to keep them from pulling out and doing an exit scam? The solution seems to be physical wallets like the Ledger or Trezor, but what is to keep the developers from putting a backdoor into the software that drains all coin once it reaches a certain amount, or to take fractions of a coin without leaving a history of such? If only have 1-2k in it thats not a gigantic hit, but lets say you have millions in coin. Is there nothing more secure one could do?