market capacity alone is just one parameter. If there is no demand, a low market capacity won't help. Price goes up because of supply and demand. I've been following Bitcoin since 2013 and every time it went up people said the same thing: too expensive, reached its maximum capacity, not a good time to invest (and I also sold some way to early). But to bet on Bitcoin alone is also not so smart, that's why I recommend creating a diverse portfolio, but I would still keep Bitcoin as part of my portfolio. I don't think it reached its peak yet.