nothing is certain but the unforeseen
It is impossible to be absolutely certain what will happen in the future. I wouldn't be so sure that investment will pay off like you expect. Nothing is certain in this life but the unforeseen. Nothing is certain but the unforeseen, so if you spend all this time worrying about and planning for what might happen, you're going to miss out on everything life has to offer.
Nothing is certain but the unforeseen.
Prov. You cannot foresee what will happen. Jill: Now that we've got a new boss, this is certain to be a nicer place to work. Jane: Nothing is certain but the unforeseen.