Narrative:
Solana validators are expensive and subsidized by Solana Foundation.

Narrative breaker:
I started a new validator this year. Took 0 stake from Solana Foundation (too lazy to apply for a year long waitlist tbh). Achieved net profitability within 5-6 months. Now sustainably running at 0% commission.

is there a variable to profitability when commission 0% beyond self stake? given reasonable commodity cost to buy or rent validator if you are 0% commission then you just need x self stake to break even?

I think you are correct about that. Theres also block rewards which happens even with commission at 0%. So for example I topped off my validator to have ~60 SOL to cover a couple months worth of vote txn fees back in mid-October. It still has 60.41 SOL today. Block rewards have entirely been paying off txn fees.