I guess that both of them have personal interests that didn't benefit him and the other and so, the conflict goes.
Of course, it's all about personal gain, and once the benefits are no longer shared equally, conflict is inevitable.
Elon and Trump's friendship is based on benefits only, because the past shows that their relationship has more disagreements and criticism than a constructive and close relationship. Their relationship did not really improve until the 2024 US presidential campaign. It seems like history is repeating itself once again in their relationship as it no longer benefits either of them.