It’s happened to me many times. That’s why I think it’s better to do the opposite: start with a decent capital and aim for smaller, more realistic wins. It keeps you grounded and helps you manage your emotions better.
The target most gamblers set are my mostly delusional and unrealistic and it all springs from the fact that they assume that winning big or things working out the way they've planned it to us usually very easy. If everyone that hopes to win big like you eventually does that, where will that place those running gambling businesses?
One things I've always had at the back of my mind is that most times, a lot of the things I'm hoping to try out in a bid of proving that I'm smart have prior to my entry into the gambling space been tried by others who most times have lost in such trials. You can wish for certain height as a gambler but you can't dictate what will eventually play out above what has been designed to happen. If you're lucky to win, good for you and if you set a target and it works for you, that's also good but if all you've planned for didn't work or your bankroll is not enough to meet all the things you're expecting to bet on, it's best to focus on what you can control and not what's above your control.