the sort of adventure that in reality is scripted to the nth degree and planned by researchers and backed by crew who will instantly fly you out of any trouble. It's not reality.
So because you've not done it you're an expert on how other people do an adventure holiday. OK then...
Some adventure holidays are sherpaed and have guides because you simply wouldn't want to do them without. E.g. I have no intention of trekking to mount everest, but if I did, I would ABSOLUTELY want a guide with local knowledge.
Some trekking holidays are staffed because people new to it want phasing into it.
Many skiing holidays have instructors..m shock horror hwo scripted and TV of people.
Many activities like water sports that people may do on a more active beach holiday have instructors who can help should something go wrong.
There are some supported long distance bike rides.
Most people who long distance cycle tour just do it themselves unsupported having built up confidence in the UK.
Some backpacking holidays are very much in the vein of gap yahs types.
Others are self supported. A friend of mine did unassisted back backing around south America. I would probably not do it. She's fluent in Spanish and was happy thay she could deal with most situations.
But for all the people crying about how people don't like beach holidays, there sure is a wealth of knowledge about how scripted other people's holidays are.
And yes, my adventure holiday is planned to the nth degree because if I don't travel far enough on each day I won't get to the airport on time and then I'll miss my flight home, which you know is sort of important.