Have you ever used a cryptocurrency exchange? I admit, there have been some bad actors in the space as there is in any nascent technology, but at this point there are a number of legitimate and even regulated exchanges in multiple jurisdictions.

You can easily look up the volume traded on these exchanges. There are still some shady exchanges out there so I’d mainly look at the more trusted/regulated ones like Coinbase Pro, Bitstamp, Gemini, Kraken etc.

Strike has already released a working app for US customers that I’ve been using without issue for payments to friends and family as an alternative to Venmo/PayPal.

I guess you still haven't explained where the liquidity is coming from. Coinbase and the rest explicitly call out the fact that there is NOT instant settlement, and that your request may or may not be fulfilled at the agreed price.

That means Strike needs to have reserve currency to cover any fluctuations between the time they "instantly settle" your transaction, and when they actually are able to convert that into USD or Euro or insert currency at an exchange.

I keep getting downvotes and yet nobody can explain the magic handwaving to me with anything other than "but my transaction worked". It's great that's working when their transaction flow is probably measured in the hundreds of thousands of dollars, but plenty of pyramid schemes churn along just fine until they grow.

I believe Strike is upfront about the fact they are using the stable coin USDC at the exchange for that part of the transaction. USDC is backed by Circle and Coinbase and is probably regarded as the most trusted centralized stable coin. The downvotes are probably because of the “intrinsic value” and Ponzi scheme arguments which people that have been in this space for a decade have grown tired of.