Some people think problem X should be easy. Then they get frustrated when it takes a bunch of time/effort/etc to solve. Sometimes they complain about the difference between their initial conception of the problem and the reality. Sometimes they give up entirely.
If a problem turns out harder than you expected, you can reevaluate if it's worth the effort. If the reward for a solution is minor, then it could be reasonable to do something else instead. But don't think the problem is being harder than it *should* be and get offended by that. You were wrong about how hard the problem is or how skilled you are. Accept that reality and change your mind appropriately.