Seems kinda selfish to risk your family's wellbeing for the sake of your business dream.
It seems like they are giving their children a chance in life that is a little less morbid than waiting to inherit half a house.
That there might be better ways doesn't mean they are as bad as the average. I'd take 4X at these odds at 10X the average UK salary (even if 2 of them might be short careers) and a possible business over a less than certain chance of 2 mediocre UK employee lives with not as many family obligations. But each to their own.