I don't know if somebody "around here" knows something they aren't saying
but I don't think fires
originating inside the cockpit are at all common.
Maybe a laptop or some other appliance might catch fire...
A much more likely issue is a fire forward of the firewall, fuelled by a fuel leak. This is why the firewall should be made of steel, fuel hoses should be fire sleeved and properly secured so they cannot touch hot items, the exhaust system should be leak-free, etc. And the cockpit heater controls should have a clear all-shutoff position which blocks all gas routes through the firewall.
And obviously electrical wiring needs to be done and secured properly, and done using high-temp insulated cable.