It's a terrible idea - do it anyway. Experimentation is how we learn.
If you have a reasonably modern multi-core system you probably won't even notice a performance hit. The biggest drawback is that you have a single thing that is holding all your eggs. So if an upgrade goes wrong, or you're taking things down for maintenance then everything is affected. And there can be conflicts between required versions of libraries, OS, etc. that each service needs.
Separating services, even logically, is a good idea. So I'd recommend you use containers or VMs to make it easier to just "whelp, that didn't work" and throw everything away or start from scratch. It also makes library dependencies much easier to deal with.