In my opinion, it's not gambling if you don't stake something valuable, something like money or what you can sell for money. Time is a valuable thing, no doubt about that. But if we go fishing, risking to lose our time and get nothing in return, we don't call it gambling, do we? No one does.
The example in the OP is gambling related, but we shouldn't call it gambling if nothing is at stake, I think.
You're correct, if we use time consuming is a form of gamble, I think most of activity in this world is called as gambling, then all countries should legalize gambling because accept or not, you're live with time.
But stake a valuable thing isn't always gambling, we need to know the original source he get. Someone who's gamble using valuable coins e.g. Bitcoin by claiming through the casino faucet isn't called as gambling
since he's not risking anything, he get the coins by free.So, if someone obtained something for free, like inheritance, for example, and he/she put that at stake, it's not gambling? I don't think so. Money from the casino faucet is still money, and although anyone, surely, can easily afford to lose that money, when they put it at stake, it's gambling, in my opinion. But if we take into account that you can't withdraw the money from the faucet, so, it's not actually ours, then it's a philosophical question, whether it's gambling or not.