AIBU to expect cyclists to use the cycle lane?

[Riddlemedee]

I am lucky to live in a lovely seaside town. There is a very busy 50mph costal road in and out. It is single lane. There is a substantial wide , well maintained, recently renovated cycle/walk path along the whole route. But some (not all) cyclists still use the road. This is dangerous, causes huge traffic backlogs and the more impatient (stupid) drivers take risks when overtaking the cyclists. I can’t see a reason why they would still use the road, any ideas anyone?

99.9% certain I live in this town and the OP is certainly in the right here. The cycle path is extremely wide and has wooden posts all along it separating it from the road. You could easily have two people walking side by side and they wouldn't have to step out of the way for an oncoming bike. It's just had a fortune spent on it and is smooth all the way, no weeds or debris.