because you can't afford both. you have to choose your priorities. you can choose to vacation, or save for a home.
but we live in an economy where a lot of people are choose to vacation and then sit around being bitter they can't afford a home that they want when they spend all that money on something else.
oh, and further, they also don't support new construction because they think new construction is bad and drives prices up and if they can't have that new home nobody else should... which further restricts housing supply and drives up prices.
the point is humans are stupid and make bad choices, both short term, and long term, and they refuse to make better choices that would improve their lives because emotional gratification in the here and now is always more important to them.
FWIW, I grew up in a family who never took vacations but we were able to own a home, though it was rural and my dad commuted 3-4 hours a day to his job. If I point this out to people today, they basically lose their shit and say they'd rather never own a home if it meant they had to stop going on vacations multiple times per year, let alone live so far away from their job to find affordable housing.