Don't understand this at all. If you have a static site (Which a blog should be), CDNs will allow you to handle practically unlimited traffic for free.

Even without a CDN you can host the static files in a bucket for practically free.

Heck even serverless platforms usually give you 1M function calls for free each month.

Cost is not the limiting factor.

The blog is using cloudflare and it is very easy to setup caching rules to optimize the site.

Sadly I have been noticing non optimized sites at lot more now.

It's definitely a function of expertise. You could get a free host that could totally handle the hug of death. You could know how to deploy a static website more efficiently.

attempting to reduce X to “just a function of cost” will almost always “work” - if one assumes themselves experienced enough to know how to spend hypothetical dollars.

the amount of traffic a website can handle is impacted by both. with insufficient experience, website won’t scale, money won’t be spent.

There are a bunch of tradeoffs--cost, cost predictability, control, redundancy, flexibility, etc. Money isn't a magic wand as you say and, honestly, I'm not sure how much extra I would pay in general on the off-chance that a blog post might go viral every 10 years--if that is indeed the tradeoff.

The cost to host a blob of text on the internet is ~0. Not being able to serve a handful of HN requests is 100% about effort and experience.