"Why is this coin not taking off when so many big names are supporting it"
I can only say that if something should happen, but has not yet happened, there is a good chance that it will happen.
My own take is simpler. This is a locale that's supposed to prize peer-to-peer and decentralization. The ideals, admittedly given a lot of lip service, neverthess attract people far less likely than most to defer to the opinions of the old reliables.
So, even the best endorsements more-or-less fizzle around here. When "it" does happen, Monero itself will capture people's imaginations.