I’m always reminded of the quote at my mechanic’s “the reason it only took half an hour is that I spent 10 years learning to do it that fast” [paraphrase]

If you’re actually an expert in something you will be able to assess (ask the right questions) the scope to 95% probability (yes there are always edge cases)

I suspect if a professional installer had surveyed the situation he would have immediately looked for hose length, holes, have the tools etc.

It seems like this is more a case of dunning-Kruger than anything else (and trust me I’ve been there “I mean how hard can it be to X”)