Until you have enough visitors or evil AI bots scraping your site so that it crashes, or if you're using an auto-scaling provider, costs you real money.
The problem isn't in markdown→HTML conversion (which is pretty fast), it's that it's a first step in adding more bells and whistles, and before you know it, you're running a nextjs blog which requires server-side nodejs daemon so that your light/dark theme switch works as copy-pasted from stackoverflow.
For blogs, number of reads vs number of comments or other actions that require a server is probably on the order of 100:1 or 1000:1, even more if many of the page loads are bots/scrapers.
> SSGing your personal site is the first step to handing it over to 3rd party services entirely IMO.
Why? Your interactive/feedback parts can be a 10-line script as well, running on the same site where you'd run Drupal, Joomla, Wordpress, Django, or whatever.
Looks like Jeff plans to do exactly that: https://github.com/geerlingguy/jeffgeerling-com/issues/167