There is nothing in what I wrote that implies people value their lives infinitely. People just need to value their lives highly enough such that flying on an airplane (with its probability of crashing) has a negative expected value.

Yes, that is the point.

Your claim that people flying on planes are engaging in an activity that has negative expected value flatly contradicts standard economic analysis and yet provides no supporting evidence to justify such a wildly controversial position. The only way your claim could be true in general would be if humans placed infinite value on their own lives. Otherwise it depends on details of why they are flying and what value they expect to gain if they arrive safely and on the actual probability of a fatal incident.

Since you didn't mention in your original post under what circumstances your claim holds true you did imply that you were making a general claim and thus further imply that people value their lives infinitely.