A lot of people have broken risk/reward logic. Yes, the chance that you have explosive diarrhea on vacation is probably very low, but the negative impact in the event it does happen is very high and the effort required to mitigate that risk (packing an extra pair of underwear that takes up practically zero space in your bag) is minimal. It's a less dangerous version of "covid has a 99% survival rate so I'm not going to waste 10 minutes to get a free vaccine"
A lot of people have broken risk/reward logic. Yes, the chance that you have explosive diarrhea on vacation is probably very low, but the negative impact in the event it does happen is very high and the effort required to mitigate that risk (packing an extra pair of underwear that takes up practically zero space in your bag) is minimal. It's a less dangerous version of "covid has a 99% survival rate so I'm not going to waste 10 minutes to get a free vaccine"