ChatGPT has also most certainly not been selling services on Fiverr by itself, but I have seen comments that people are already using AI tools to get all the jobs from Fiverr. So learning to use ALL the necessary AI tools which help you do your work more effectively, and learning them really well, might be the most important skill there as well.
From the video about the AI coding tool called Devin:
"Google's AlphaCoder, which currently beats 85% of competitive programmers, does that by using an LLM to generate thousands of possible solutions in parallel, then picks the best one."
"In the future, you'll be able to post a job just like you would on Upwork, and 10 minutes later, Devin will come back with a thousand different apps, and you can choose the best one."
"In fact, Devin is already doing real jobs on Upwork and getting paid for it, so I guess that makes it official: they took our jobs."
"Devin can learn new technologies; it can build and deploy apps; it can fix bugs in existing codebases; train its own AI models."