You have to consider pressure and area. On submarines, we have high pressure compressed air at pressures well beyond 3000 lbs. How big are the lines that carry it? Hmmm.......less than a 1/4 inch. Area ,son, I say area.
That's what it's all about,ya see? (Foghorn Leghorn lecturing on engineering).
Making a strong enough pressure vessel "To Live In" , is quite an engineering chore. And it has to be LIGHT ENOUGH,See? LIGHT WEIGHT. It is the very essence of aviation engineering and especially Aerospace engineering.
The bigger something gets under pressure, the more it wants to disintegrate.
Yes, you can make it stronger, but....can you boost it into space?
Can you move it some place besides LEO? Ha! Can you "Land" it somewhere????????? Now you have set for yourself a genuine problem.
And this one isn't going away any time soon.
Dan
PS: Oh....by the way: A space craft in a vaccuum has the equivalent of 30 lbs. per square inch as compared with the same vessel on Earth.
Now you've heard..............the rest of the story.
Good day.