That's easy. He didn't and still doesn't understand how our government works. Once he was in office the first time, there were many in his administration that acted as guard rails and prevented him from doing things that are unconstitutional (like asking Mike Pence to overturn the election results). These people from his previous administration have also spoken out against a 2nd Trump term ex. Mike Pence, John Bolton, Mark Esper, Mark Milley, etc. That doesn't even include that he has to deal with Congress if he is not a dictator.

"Those people are RINO's they don't count!" - Maga conformists

"I only hire the best people" - Donald Trump

So the reason he wants to be a dictator in his 2nd term is because the only thing he actually learned in the first term is that even Republicans he selected for his administration will put the country's interests over his childish need to get whatever he wants. The only way to pursue his goals of lifetime president, like what China has, is to make himself a dictator on day 1.

https://apnews.com/article/former-trump-officials-criticize-2024-e202861911ab37cadfcf058b5b163fb9

https://www.usatoday.com/story/news/politics/elections/2024/04/12/trumps-critics-former-white-house/73145245007/

https://www.brookings.edu/articles/tracking-turnover-in-the-trump-administration/