This is very correct, but it's actually a two way thing, we could turn our 5k to 10k and may aswell loose it all at some point. Sometimes one can be actually lucky and they would do that just with a stake and it will feel like a flip and the other the person may even fail at several attempts but very importantly is making sure you don't get too emotional with it so you don't give a chance to addiction at some point.
We are not talking about one or several bets, I think the point is to do it safely and without the risk of losing the entire deposit for one bet. If this is so and the point is to achieve such a goal safely, but honestly, if the goal is to increase the bankroll 10 times in a year, then without risk it will be very difficult to do, especially if we are talking about bets with big money. In addition, you can not win constantly, one day will be successful, on another day you can lose, that is, it is not as easy as it may seem.
It is just one of those things that are not possible, trying to earn that amount of money as an investor is incredibly difficult, trying to do so as a gambler is even more difficult, and that is assuming you are a gambler which can play with an advantage over the house, because if this is not really the case then it become impossible to achieve such goal, as the games offered by the casinos are mathematically on their favor, and any attempt to beat them will end up with the gambler losing all their money instead.