i was present for multiple big poskim of America answering this, as well as been in a camp where they asked one of the gedolim:
1- Def nothing assur whatsoever with wearing them.
2- There is a heter when there is sufficient tzar caused. Machlokes on what qualifies as “sufficient”. This is heter for sports, etc. Not toluy on whether beratzon.
3- To not wear tzitzis stam, though meikar hadin not an aveirah, it is very prob for other reasons, like once e/o is noheg, mystical shmirah, loss of mitzvah, L’maan Tizkiru, etc – no such thing as personal choice.
4- In camp, etc, there is also chinuch issue – big machlokes.