The issue is not space, but how we move through it

Not sure how it works in the US but here in Oz (where water scarcity is always present in our collective psyche) golf courses are usually placed on flood plains where it would be dangerous/too expensive to build housing. In addition most allow people to walk through them and many even allow dog walkers so they have quite a lot of public amenity.
I would still prefer if they were just designated as public parks rather than having huge swathes of grass that needed frequent watering, but they're not nearly as bad as most make them out to be.
- In Germany most courses only have a few public walkways and if you leave them security will escort you right out
- Yeah, here in the US, golf courses can be extremely wasteful. There's two golf courses on my drive into the city, one is on a river floodplain, the other is a HOA golf course full of sprinklers that could absolutely be more housing. If I go the other way, there's another HOA golf course that could be housing too. So, to start with, there's three golf courses in a 15km radius.
  One of the HOA ones is exclusive access to the surrounding retirement community, the other HOA one doesn't have a fence or anything, but idk if they chase people off. The one on the floodplain you have to pay to access the grounds.

Now add in mixed use zoning, and affordable housing units and this could be a winner

I work at a golf course and I'd rather be doing something meaningful like building homes so this post speaks to me directly.
Unfortunately the big thing lately is we've been dropping a bunch of trees.

If you just repurpose for housing you just wind up with 40,000 people needing transit and overloading the system you're trying to promote.
We need to think beyond housing and towards having communities that largely provide the needs of the people living with them. Shops, offices, other non-office/shop jobs, and recreational activities need to be considered as well.

Most suburban streets are 50 feet wide, many suburban front yards are 50 feet deep. That's a wasted space 150 feet wide and however long the street is long. Think of how much housing could be built in that space if you tore up that road, and in its place put a pair of alleyways housing in the middle
- Good luck with the NIMBYs. Or NIMFYs now I guess?

Not for nothing, but this wouldn't fly in the USA. You'd need to replace most of those trees with roads.
Or better yet, reduce the number of housing units and keep the trees.
- This is Seattle btw, but I think the meme is that it won't fly.

What if we just altered zoning laws so they don't restrict high-density residential buildings?
- Oh, they didn't change that, people living there need to get real good at dodging golf balls.

Yeah but then rich fucks wouldn’t have a place all to themselves to be rich fucks, so that’s a fuck you, poors, just be rich like us, thanks.