I don't know about you but sometimes I sit and think about how my life would be different if I was wise enough to buy up alot of domain names back before the internet became as big as it is now. URL's with 3 and 4 letters that everyone is looking to grab is selling for crazy amounts of money. Fast forward to today, since we can't rewind time, how do you re-adjust to the times and find out what may become a big hit later? For example, I sometimes play around with unregistered URL's and try to figure out what MAY be profitable later. Like what if you bought ebay.com months before they became a household name or before they existed? Do you think that since ebay.com was registered to you already they would of tried to find a different business name or do you think they would of put in an offer to buy your domain?
You would have to have a priori knowledge about which companies would be forming and what names they would be using. To register a common name in advance that they needed would be like playing the lottery, unless it was such a common name that it had at least a few hundred or a few thousand dollars behind its value for simplicity. If you owned buy.com or restaurant.com then you know you're going to get money out of that, since it's a basic word that everyone would want to have for many types of business models. If you registered whitetigershoes.com and there's no such company or people weren't even interested in white tigers, then if a company did form they'd say "well, that one's taken. I guess we'll go with wtshoes.com since it's shorter or white-tiger-shoes.com instead since it's the same thing anyway", and they usually do.
It isn't the name that makes it worth money, but the value behind the name before the company can get to it that makes it money. People may think "hey, I have ebay.com so now I will make a fortune!" only to find out that the company decided to register e-bay.com instead.
They may offer to buy it later for pennies compared to what it's worth, since they may still want it and it can't be legally used for profit if they trademarked it, but the real value is in having common domains that can be used anywhere or (if lucky) having just one domain name that the company needs and has no other alternative to.
If you can find that, then you will make a lot of money off of it. Even if it's only temporarily owned. Recently, someone registered Google.com through Google Domains by mistake and was paid $12,000 by Google to get it back. They only had it for a few hours, but they made $12,000 for it.
Sometimes even an error can make you money if you do it correctly!