Who actually loses if stocks skyrocket up?

For real estate, if home prices skyrocket you could argue that lower income or younger people won't be able to afford to buy a house. Even people who currently own may not be able to pay property tax any more if it goes up too high. So it could be argued that real estate prices skyrocketing would hurt a fair number of people. Don't get bogged down on this example...

My question is which population subgroups would be hurt if the stock market skyrockets and continues to do so?

The people who are shorting the market obviously.

The people who are not invested just wouldn't benefit but would they necessarily be hurt?

Anybody else?