So what makes BTC and LTC better than anything else?  OP states they are both "better supported"....well, going off that, if another alt is "better supported" wouldnt it overtake BTC/LTC? 

Its like saying you should only buy gold or silver, but not diamonds, rubies, emeralds, or oil futures or apple stock.  they're currencies and will be worth whatever the market provides.

what about 42coin that is worth what 100x BTC?