I owned no bitcoins at the time I desired to trade bitcoins for a physical product (in this case: ~7g of Cannabis)
What recourse do I have that does not require trusting a third party?
I do not own the required compute power to mine it myself (not technically true at the time, although certainly true today)
I'd like to have you walk me through the exact set of steps to acquire my bitcoin and use them to purchase that physical good, where I can magically avoid placing any trust in a 3rd party.