"Stupid" ideas for quite good investments

Hello! There has been a lot of talk recently about the alternative investing. At first glance, these are sometimes stupid ideas, but as they say, if something is stupid and it works, it's not stupid :D In the last 15 years, you could earn even more from these bricks than from stocks or gold, because there is a demand among Lego lovers for well-preserved sets that are no longer produced. I've also heard a lot about investment wines. My question - what do you think about such ways of investing? How to estimate the risk, how to predict the future demand for something? Or maybe you have some ideas for "certainties" in such alternative investing?