I'm biased but I'd go with .NET if you actually want to get the thing built. Obviously use a new stack if you want to use it as a learning experience.
With .NET Core and Postgres you can get something stood up within a few days and host on a cheap Linode, Digital Ocean or another provider's box for $6 a month or so. That should last you scalability wise until you have enough money from it to do something else and gives you type safe, performant code.
It was a while ago now (I can't remember the last time I ssh-ed into the box) but I set up my blog using this guide [0].
I just logged into Digital Ocean to check, I'm running a single 512 MB memory droplet with a 20GB disk for $6 a month and apart from getting familiar with Linux (especially managing user permissions correctly), setup was easy, I run an Nginx reverse proxy in front of a Kestrel instance but I know people have said you don't even need Nginx.
I also used Let's Encrypt for a free SSL certificate and setting that up to correctly refresh on a CRON job was the hardest part of the whole thing.
I've no doubt the site [1] would fall over if it ever got anything like the HN hug of death but this would be easy to plan for assuming organic growth, I imagine there are fairly easy ways to set up load balancing for droplets on DO and moving the database onto a separate droplet etc should give you enough headroom for scaling.
The code [2] is way outdated now and awful quality but it's on GitHub.
Others who have more experience may say it's worth learning a certain cloud feature or serverless stuff but my gut feeling is it's better to get the thing out there and worry about that sort of stuff when you get there.
Edit: It's worth mentioning that [0] talks about developing the site on Linux, though I did that just to get a feel for Linux it's not at all necessary and much easier to do the development on Windows with Visual Studio then all you need to do is:
dotnet publish -c Release -r linux-x64
To get a published site to run on the Linux droplet/machine.
With .NET Core and Postgres you can get something stood up within a few days and host on a cheap Linode, Digital Ocean or another provider's box for $6 a month or so. That should last you scalability wise until you have enough money from it to do something else and gives you type safe, performant code.