This isn't as it seems.
None of the other major parties stood for election in Clacton, which meant that all those tens of thousands of votes cast for the other parties at the 2024 election should have gone to Binface in protest to make Farage fail. And the volunteers who would normally be canvassing for those parties should have strategically been out on the street trying to get votes for BinFace or another.
But instead the voter turnout remained similar to 2024 levels (around 40% at both elections), which means the voters who turned out were either new voters for Farage, or the voters of the other parties voted strategically for Farage.
My guess is that the other parties decided Farage is so fatally damaged with the ongoing scandals, that keeping him as Reform Leader is their best bet at maintaining the usual 2-party state (and more so as there is an paused parliamentary investigation into Farage that would resume only if elected).
It is of note that Reform's popularity and Farage's popularity nationally is on an ongoing decline and if Farage had been voted out, Reform could have either imploded (thereby allowing another right/far right party to replace them by the time of the next election i.e. the Elon Musk backed Restore Britain) or had a change of leadership at Reform UK with Farage stepping down
There is also the question of whether Farage is controlled opposition acting his part to give artificial hope to the people of change.
The truth is the 2-party state has existed for years and given the deep-state in the UK predictable control. If that system was broken, then it's a risk of major change to the establishment/british aristocracy.