Unless you reviewed all the code yourself your are trusting the devs. You also are trusting the devs that they are maintaining the software without bugs. You trust the security from the miners that they don’t “ally “ and start excluding transactions based on government requests. Killing one of the main feature of the network (being permissionless). You also trust the “network effect “ to keep growing and don’t start a downtrend that left your savings on 0. Those 4 examples are the biggest but I’m pretty sure there are more trust involved.