It's not impossible that Farage got high on his own supply and genuinely believed that if Starmer went, he'd be kissing hands the next day. Instead he's still one step away from the succession.
Or - (if you prefer a narrative much more in keeping with Farage). Having spent the past two years telling anyone who would listen (whether they wanted to or not) that he is the UKs next PM, then when Starmer goes, there could be a lot of people with lighter wallets wondering quite what they got for their £5,000,000.
And it's possible for more than one thing to be true at the same time.
Also Farage has now had to try and smarm off 3 by-election defeats looking more and more shifty as he does. There is a very real laaw of diminishing returns.