Actual annual numbers for 40 low-traffic content sites.
Shared (cheap host): $380/yr. Fell over twice during traffic spikes. Support was a chatbot.
Single VPS, self-managed: $640/yr plus maybe 30 hours of my time. Never went down. I became the support chatbot.
Managed WordPress: $4,300/yr. Never went down, never thought about it once.
For 40 sites that each make $50-300/mo, the VPS is correct and the managed option is a luxury. At 5 sites making $2k each, managed is obviously correct. The crossover is about where your hourly rate exceeds the price difference, which is a boring answer but it is the answer.
Infrastructure nerd. Proxies, VPS, headless everything.