Supporting bitcoin or other altcoins is technically the same since you are supporting the same technology and ideology , yet we now experience a huge gap of value between bitcoin and other altcoins which make it a bit doubting to whether invest in those or not especially on the short term run .
As for the long term run investing in those coins is a must since bitcoin's supply will eventually end one day because it's capped to 21M coins and other coins doesn't really have a supply cap so that will be a double edged sword for them for 2 reasons :
1- It'll be much harder to scale .
2- It'll be always available (especially when bitcoin won't be anymore )  .  

So it's really up to the investors to make the call to whether they can wait to get profit or not and in my perspective a person must at least choose 3 or 4 out of the 1000+ altcoins to invest money in them in case something happens to bitcoin , then we won't be completely zoned out .