There's nothing wrong in staking high as long as that's within your capacity then you don't have a problem...but betting with high amounts of money poses some certain risks especially if you are the type of gambler that likes to keep on staking immediately after losing...this would make you lose more than a bettor that sticks to betting with small amounts...staking high only increases the risks of losing more
But it also increases the potential amount of winning. And that's what they're probably thinking why they like to stake high amounts. Can't blame them for that if they're only positive thinking of the possible returns than the losses. They're used to that system and that's why they keep on trying it again and again. And no matter how high they lose at the moment, it won't stop them from restaking with a higher amount for them to win back their losses and at least got some profits if ever they become lucky. Nothing wrong with that as long as they can afford to lose it. But yes, in the long run this isn't sustainable and so balance your bets and the strategy that we do should depend on our bankrolls too.