Such huge winnings with minimal investment in the casino are quite rare, so everyone knows about them, many bet small amounts in online casinos in the hope of getting a luck slot with a seven-digit figure or more, so I think these are unique examples of luck, but they are also motivating factors for many gamblers.
indeed, basically playing gambling is betting on luck, and as the OP mentioned are some people who are lucky when they bet with a small minimum and win with big profits.
actually not for motivation, but as an example of confidence when gambling one day will definitely find a big win luck. even if you have to lose more money first
I think that confidence and motivation are somehow linked to each other. If you are not confident you won't feel like playing a gambling because in your head you will say that you will still lose so it would be better if you can just save that money or use that money in more valuable things. The same goes to motivation.
Those who continue despite of their previous losses are either playing for fun or they are simply motivated/confident that they can recover all their past losses once they win a really huge amount in gambling. It can be though jackpots or they will hunt a massive multiplier or they can build their balance from the bottom to the top slowly but surely.