But the rich party donors don't actually mind their party losing as long as they also control the second party well enough to avoid regulations, taxes, or any modicum of responsibility towards society.
FPTP isn't about which party wins, it's about reducing the power of the electorate far enough that change only happens with the content of the rich.
It's only temporary. Once they've bribed farage sufficiently he'll disband the reform party and the tories will return to dominating elections through the corruption of FPTP. The absurd thing is Labour refuse to accept this and will blunder on refusing to accept we need a proportional electoral system