Im unsure about why you ask me that question, and its not always easy to show restraint to argument bait.

So look, I am simply one kind of client - i enjoy buying things i know i want. I buy certificates, and software as one thing, using a single payment, if i choose to. I dont like “cancel if you like” trials, or running subs.

lets not turn this into what it isnt.

Selling things for a fixed price Is an established model. Coders get paid in any form they choose to, by those who want the service. I simply told the OP what model works for people like me, and in not alone here. OP is infact under no obligation to listen to me.

i saw his product, said its good, and gave him my take on it.

You are welcome to yours.

Honestly it's more of a full-time job than just a skill.

The long way: A master's degree or PhD in Human Computer Interaction or similar field, frequently doing things like usability testing, user interviews, statistical analysis, thematic analysis etc. Not joking, this is what I'm currently doing. Coming from practicing UX in industry, I thought I wouldn't learn much from academia, but it's been eye-opening.

The short way: Read About Face - Alan Cooper, then try and do some of the techniques in there. It may seem excessively detailed, but frankly it only covers a small portion of techniques that UX researchers actually use. This is really quite a shortcut but it will get you started.

You could have fake interviews with clients as chat bots. It wouldn’t have to be a great bot as clients often ignore your question, give very vague responses. As long as you had a few responses lined up that had to be triggered by asking the right keyword. Eg “target audience” or “budget”. You could probably recycle or generate responses by slot filling different values for template answers based off a little properties table for each client. The designers goal is to try and extract info to make a more functional brief before starting work. Is there a rating system for submissions? Why would people do these projects vs. those sites that have a marketplace for logo design where the client just pays for the one they like?