Saving up $100k/year towards ownership is just treading water; prices will easily rise that much on their own. This leaves another ~$70k/year to play with in your $300k salary. The marginal cost of living alone vs. with roommates is not insignificant in that context. So yes, if you are making $300k/year and serious about buying, it would be hard to justify renting an entire apartment.

Absolutely agree that you can afford to live alone if you do not particularly care about buying.