In the math you laid out, you have to get 6 subs a year for 10 years on your $600/year plan in order to recoup your investment.
Why would this tweet generate leads for 10 years? Why didn’t you figure discounted cash flows into the calculation? Will 36K be worth 36K in today’s money 10 years from now? 10 months from now?
And now, your hosting provider is rate limiting your website and returning 429. All this HN traffic is going down the chute. Perhaps you should have spent some of that cash on a more robust hosting plan?