A giant gas cloud does not remain in equilibrium. Because its density is not uniform some parts of the gas cloud will clump.
This can be tested easily enough. Just blow. When you exhale rapidly, you create a volume of high pressure gas. The gas will not clump together. It will do what everything always does: it will seek equilibrium.
The pressure will disperse.
Worse yet, things that obtain equilibrium always stay right there until something happens. Your second sentence is actually incompatible with your first, because if the cloud is at equilibrium, by definition there are no uneven densities. But even if they were there, they wouldn't violate physical laws.
If these clumps are massive enough the clumps will get denser and denser because of gravity.
This is backwards. The more gas is compressed, the stronger it fights compression. Gravity gets weaker with distance, exponentially weaker. So a bigger cloud just makes it more absurdly impossible for gravity to be able to overcome pressure.
If there is so much mass that gas pressure cannot resist the clump getting denser gas pressure will lose against gravitational pressure. At some point the gravitational pressure will create so much energy that fusion can take place.
Gravity is not energy. Neither can gravity be converted to energy, let alone create energy. Rather than review basic physics, I'll just point out that if gravity were energy it would be a trivial matter to create perpetual motion machines. Surely we'd have no need to burn oil or coal with such a handy, abundant supply of gravity at hand.
Now nuclear pressure fights off the gravitational pressure until all of the elements in the gas have been used for fusion and only non-fusion elements remain (like iron or something).
The next barrier is Pauli pressure, then baryonic pressure. If the clump is large enough to pass the baryonic pressure barrier there is no known pressure that will stop the clump from growing denser forever (at this point you have a black hole).
Advances in science are happening every day. Who's to say nobody will be able to make up a way to overcome the black hole pressure?
If you want to verify this go drop an apple off your porch? Did it fall? Verified.
Ah! With such logic, it's easy to see how folks consider big bangs & evolutionism in general to be fact. Just posit an experiment that says nothing whatsoever about the question, and viola!
(A yes-no test of gravity does not measure its relative strength, for those who didn't catch the trick.)
If you have enough mass in a small volume gravitational forces can and do overcome all gas pressure forces. Of course we can demonstrate it with the Earth because it is very very tiny compared to the volumes we are talking about. Pressure is just a force per unit area. Consider a gas with two particles: So if gravitational pressure P~M^2/r^3 is greater than gas pressure p~k/r^3 then gravitational pressure wins. We can see that this can be accomplished for M>>k. Considering that the masses we are talking about are 300,000 times or more massive than the Earth this is easily achieved many times over.
What we can
demonstrate on Earth is that gas pressure is stronger than gravity pressure within the spectrum of terran limits. We can also demonstrate that gravity becomes weaker with distance, so it has no hope of ever "catching up" with gas pressure. Fantasizing about bigger and bigger clouds of gas is not helpful. It's like saying "I can't jump to the Moon, and I can't jump to Mars. These distances are too small. We need to posit a nearly infinite distance; then I'll be able to jump that far." Venturing into imaginationland does not help gravity overcome gas pressure - it only makes it more absurd.
Y'all really need to come up with a better story. I think you could get better returns from a surface tension hypothesis - not enough to work, but certainly closer than these gravity stories. Maybe a quantum resonance gimmick? You know, spontaneous cooling in one (vast, vast) region, coupled with spontaneous heating in another (equally vast, vast) region - something that might plausibly condense the gas significantly?
Now I know folks believe what they want to believe, but there's one part that makes no sense at all. If, as they say, right after the big bang there was just one big hydrogen cloud, why didn't all the hydrogen get pulled into one single body? If gravity can overcome gas pressure, given enough gas, then surely all the matter in the universe would be able to pull it off. But if even that
isn't enough, how can anyone believe lesser clouds are able to do the job?