Farage is a bit like Jeremy Corbyn, by being more successful standing and shouting at the sidelines stirring the people and getting popular without having to actually DO the work. (Please note, I'm not suggesting their political views align in any way whatsoever!).
Does he want the PM job? Well, it's not necessarily that clear as perhaps he wants the job from an egotistical view, like Boris Johnson, even if he wouldn't actually do much - a bit like Trump. However, I think he'd be quite happy to just grift and make a load of money along the way - as he's doing, and will do even better than anyone else if he secures £100m for Reform (in which case, he'll keep the grift going). It's not clear if Elon will support Reform or want to try and get control of the Tories, using Reform to keep the party from daring to move back towards the centre ground (and IMO become electable again).
Farage had to get his foot in the door and used Reform to become an MP, as without the MP status he can't really get anywhere, and I don't think he'd hesitate to throw the party/limited company under a bus to defect to the Tories and take over as leader of the party. There's ZERO chance of the current leader sticking it out until the election, unless it's called early for some reason (and Elon and the right wing media keep telling us all how Labour is just weeks away from collapse).