I know it's highly speculative type of investment and one should invest only the amount they are willing to lose.

That being said, I know (sort of) major advantages of BTC. Please enlighten me on the disadvantages and roadblocks it's facing short term (1-5 yrs) and long term (10-20 yrs).

Edit: Thanks for the explanations, I also found this wiki page explaining the risks involved (If anyone wants to read)