Most soft contacts are disposable, maybe All! Even monthly lenses are not very expensive. I use SoftMed and based on a years supply, they last two weeks. I generally wear them closer to three, but whatever.
I carry spares on all dive trips. If I loose one, no big deal. I try to keep my eyes closed if I remove the mask. But I've removed the mask, and squinted a bit, and they have not popped out.
If I loose my mask, then dive over. On deep dives I sometimes carry a backup, but if I loose both contacts dive over. So far with just under 200 dives I've lost.... .zero......
I did have one riding around in the bottom of my mask a few months back. It fell out when I did a couple of rapid eye movements (very rare), and there is sat for the entire 45 minute dive.