> Why is it better to let people be sickened, even if they can later sue, than put some stops up on risky behavior in the first place?
Consequentialist reason: you don't put barriers and friction in front of (e.g.) biotech and drug innovation. See the pandemic for this (FDA has killed approximately a million people alone by preventing covid vaccines from being available in the market sooner).
Deontological reason: you don't have the right to tell people what they can and can't do with their own bodies (w.r.t. products they want to consume, at their own risk, etc).
There's also regulatory capture, which reliably and predictably occurs in mixed economies (see e.g. public choice economics).