OK, let me propose the following conjectures as representative of reality:
There are not enough housing units for all people who need housing.
Population increases over time.
Construction materials, workers and equipment are finite resources.
Because of 2 and 3, 1 will always be true. Additionally, even if 3 is not a limiting factor in a particular area, it takes time to build new housing units and therefore the supply cannot easily adjust to meet demand.
Assuming you accept the above (if not please propose a different representation of reality), what is your alternative plan for distributing housing units?
There are many ideas to increase equity in the housing market. Most houses are bought by people who already own houses. They have better credit and more equity, so obviously it's easier to buy a second home than a first.
Governments could favor first time homebuyers by taxing extra homes, or just giving each person a grant for the down payment. The answers are pretty simple, but they are difficult because homeowners vote and donate more to political campaigns.
Vote and volunteer for your favored candidates, or someone else will.
Most houses are bought by people who already own houses.
You realize this doesn't mean most purchases are owners buying extra homes right? That in most cases the owner is buying a new home and selling their current one because they're moving or their family is growing?
taxing extra homes
I do agree we should be doing this, and especially making an effort to prevent foreign investor purchases of residential properties.
Vote
Yes please, in the name of fuck, everyone go vote and don't let anyone intimidate you out of it or convince you that your vote doesn't matter.
My jurisdiction levies land taxes on investment homes, but not owner occupied ones unfortunately that progressive policy is opposed by regressive policies at the federal level giving tax benefits to investment home owners
Luckily we have the ability at all levels of government to vote for candidates we prefer without wasting our vote if they have no chance of winning
2 is not necessarily true. A well developed, modern world is probably at replacement fertility rate of 2.3 or so (don't know exact number you can look it up).
Construction material needs innovation to reuse or develop ever-available methods/forever lasting shelter.
Workers and equipment.. need not change quantity when 2 becomes false.