If you own "shirts.com" then you definitely ought to make a website out of it. You have a huge advantage, and you should use it.
But if you were making a website to sell shirts, you might reasonably ask whether it's worth it to spend the money to buy shirts.com or to pick a more affordable name and save your money for other things. If you're a startup and shirts.com is in your reach, then you have a surprising amount of capital for a startup that hasn't launched -- why do you even have that much?
Definitely. You wouldn't buy shirts.com because the price of shirts.com is roughly equal to advantage you'd get using it, except for the fact that you had to pay upfront.
The only time you'd buy a domain like that is when the benefit you'd derive from it is greater than the price; However when the seller hears of your offer to buy it, goes to your website, finds out how much you'd benefit from the domain, the price would go up accordingly. In other words, only when the seller is clueless.
Same reason why Groupon in Australia was called "Stardeals" once upon a time, on a domain called stardeals.com.au.
But if you were making a website to sell shirts, you might reasonably ask whether it's worth it to spend the money to buy shirts.com or to pick a more affordable name and save your money for other things. If you're a startup and shirts.com is in your reach, then you have a surprising amount of capital for a startup that hasn't launched -- why do you even have that much?
I think that's the issue at hand.