You are right about the trade-off: A more infectious, less deadly virus is the natural evolutionary path for them. But about the breeding ground, not really: I

You are right about the trade-off: A more infectious, less deadly virus is the natural evolutionary path for them. But about the breeding ground, not really: If one day some super deadly variant evolves, it's not popping up in all of the infected hosts at the same time. It'd still need to infect everyone from scratch, and since we all have our guard up right now, it'd definitely have an incredibly hard time doing so.