I’m painting with very broad brush strokes here but, by and large, people who collect things and then brag about it publicly are doing so because they don’t have a personality or any other achievements to boast about.
It’s something that requires very little skill whatsoever. You literally just have to have the economic means to be able buy things, which most people do. It’s not an achievement. If you are collecting stuff that can be readily and cheaply bought in shops up and down the country, and on the Internet, it is even easier (and even more tragic when used as something to boast about).