Well first,

Holding your hits in for a long time is a waste, almost all the THC is deposited into your blood stream right away, so all holding your hits does is deposit tar in your lungs,

secondly, no I've never heard of anyone getting a collapsed lung from smoking a bong and I've taken some massive bong hits in my life.

and thirdly, using a bong is probably the second best way to smoke after a vap because the smoke is filtered through the water which takes out some of the chemicals, so it's not to bad for your health. But smoking weed out of a joint isn't that bad for your health so that sums that up I guess.

If you have any other questions let me know.