You don't necessarily have to use your own node if you're behind Tor and switch remote nodes often. Monero still provides very strong privacy guarantees even if you don't.

Monero is decentralized right now in terms of node count. It would be harder to run a node if it had similar tx count to BTC, but the reality is it doesn't. And if it ever does, it all depends on when and how quickly that happens. Technology progresses with time as well. Otherwise, we're just left to speculate what will happen.

Monero definitely does have different disadvantages and advantages vs Bitcoin of course