How much BTC does it take to retire? I ran $3k–$10k a month through three price paths

I built a free Bitcoin retirement simulator that models the price in cycles (peak, crash, flat years, recovery) instead of one smooth growth line. People keep asking “how much do I need?”, so I ran the common cases.

Spending starts today and rises 2.75% a year with inflation, with no more buying. BTC needed for it to last 30 years:

(BTC at about $80,700, run on 24 Oct.)

What stood out to me:

• The price path you assume does most of the work. Same spending, about 5x difference between the optimistic and conservative paths.
• Doubling the time doesn’t double the BTC. Going from 20 to 40 years takes roughly 35–50% more on the baseline and conservative paths, because the later years are paid for at higher prices. That only holds while prices keep rising: the model’s last cycle ends in 2045, after which the price levels off while spending keeps growing.
• None of these start with a crash. All three paths climb to a 2029 peak first, so the first few years look kinder than a crash-first scenario would. No taxes, fees or pension either.

The full table, including 20 and 40 years, is here, and each number opens in the simulator so you can change the inputs: https://bitcoinlifespan.com/bitcoin-retirement-calculator/

It’s a model, not advice. Curious which assumptions people here would change.