sr_banksy

I keep reading about how energy inefficient it is, both transacting & mining. Numerous banks and firms have labeled it a scam, yet they devote resources to trade in it. Out of naive curiosity:

1) Why has Bitcoin captured mainstream attention and not other viable alternatives that have been touted to be better (say ETH, LTC etc)? Is it simply first mover advantage?

2) What would it take to replace it as the de facto cryptocurrency standard?