Well don’t not buy one because you think others will see them as wanky, as that’s just silly.
You get one if you want one!
The one thing I’d say about them is that don’t seem much good if you want to actually do anything beyond walking or standing still in them. They’re not much good for being active at all in as their bulk makes them quite restrictive.
I don’t personally have one but just going by family who live by the sea and have them for their intended purpose of changing under, and what they’ve said (they don’t use them as coats for example).
We also go on some quite active holidays and see alot of tourists wearing them as coats - remember you’ll still need something to keep your feet and ankles/ lower legs dry. That’s the same with a coat of course, but people seem to think they can wear a dry robe with crocs for some reason. We wear waterproof trousers with rain coats if we’re doing outdoor stuff in the rain, and then hiking boots, but obviously wellies would do the job if you’re not planning to be that active.