Yes, there is no harm in gamble that is why when you visit a gamble house, you will see a notice that speculate that, it is only for 18+, that is free to go into there.
Gamble isn't bad but it depends on who make the stake, if he is fully aware of what he is into, then it is good but if he did it out of no knowledge, that is to say, it is bad.
In most cases, peoples who gamble their fund's have becomes rich when they know the right way to bet but there is also a truth that gamble also make some people loose a lot of money.
Those people who loose do not know the game plan or the good way to follow.
That is life, many are call but few are choosen, I said it mostly at times that, it is nice when a person go into something he knows he can do it very well than jumping into something and be claiming that he has all the ideas required to make it to the top.
Being rationale is just a matter of being understanding, knowing your capabilities and your boundaries. It is true that almost everyone have that one thing or the other that he will not like to put itself through.
That is because, no one owns all the knowledge, you see the things that makes a person to be successful in life, isn't everything but it always one thing that you need to know perfectly and you would see yourself at the top.
That is it about rationale, to think and think and think carefully if this betting you are about to bet would yield any profits.
To make it more meaningful, it is true that betting is rationale, if the one who makes the stake has took it time to study the project he is about to make the bet.
If it worth it and if it would yield the profit that he is looking for, it can only not be rationale when the person does it anyhow without looking at the environment he is surroundings with, then to know the best way to win.