That is an absolutely fair point. I am not really encouraging others to invest. And I agree its a crap shoot at $150. I got in at $115. I look at it this way - This is a known quatitiy. People want it and it has grown. is it guaranteed? Not at all. But up until now it has a stellar performance in the secondary market. I got in well enough under the current price so that I should be able to get my money back away from something catastrophic.
Looking at how this set has grown, there isn't much chance it will continue at that pace. But some sets have done this and I felt like I would like to diversify and try it out to see what happens. If this does hit $250, I will be able to pull $100 out of my investment which isn't bad at all considering. Plus investing in already retired sets is somewhat more relaxing - they are gone (unless they are redone) so you don't have to guess what's happening.
I would agree with this except, do you know of any set that you can definitely say will triple in value? Just like you, I have some thoughts about several sets and I think some are more obvious (and I have them because of that) but do we really know? If it were easy to just pick the next set that was going to triple in value, we wouldn't need others to give us advice.
I totally agree with the points, for me its just a different kind of investment. I see new sets as risk growth (still not huge risk with some sets) and retired sets (provided you get in at the right time) as more steady less-risk growth. Why? Because you take out the part where you have to guess which set is a winner.
For example, I have collected several 5887 Dino Defense sets for in the <$120 range. It just retired, has 58% CAGR and is still steadily growing month to month. I wont make out like a bandit, but there is a pretty good chance that set will hit over $200 next year. Just a different type of investment.