My point against the "multicoin" scenario is that normal people don't want to mess with multichains, different change rates, different onchain formats etc. They do want to receive, spend, save. Monero is fundamentally different from bitcoin and sure has privacy at the base layer, but that wouldn't work at the global scale either.

How am I supposed to spread the wealth? 90% bitcoin and 10% monero? Why should I hold monero for a long period of time and risk to reduce my purchasing power? 

If not holding it for long periods, what's the alternative? Is it to swap in and out from monero only when I need it? In such a scenario, i pay double the fees, it takes ages for enough confirmations on bitcoin + the 10 confs in monero. 

I like monero and if someone gives me that I'm fine. I like the adversarial behaviour of monero users.
I'm not sold the idea that a global consensus blockchain could work in a decentralized way if used by +1B people.