How to Quench a Galaxie?

If you have a gas that's really hot, where the particles are flying around with high speed, gravity just doesn't have the power to gather them together into a star. The earth is boiling off molecules right now at the edge of our atmosphere because they are too hot for the earth's gravity to contain them. But i guess, you know, the temperature is just one part of it. What of if you have a hot gas, but really dense or like a lot enough of it, or a lot of it, wouldn't that also su to create the intensity you need for a a start to form? I so you need gravity to do that work. It's like a chill process