I would avoid Coinbase. My experience is that BTC purchases with them take 5 days. You don't know what BTC value will be in 5 days. If the transaction is favorable to Coinbase the transaction goes through. If it's favorable to you, (a lot of BTC per $), then they say you've been flagged as high risk and cancel it at the last minute.
That's unsubstantiated.
I've read on reddit of people buying BTC then having it delivered even in a rising market. However, I do question there business model.
It's supposed to be buy low sell high, not the other way around. Probably heading for bankruptcy.
Yup, definitely unsubstantiated. In fact,
there was a case on Reddit recently where a transaction was cancelled for fraud when it would have massively been in their favor. FWIW, I've bought BTC at least twice from them, and when it was delivered it was worth more than the price I purchased it at.
As for the purchases taking 5 days, there's a perfectly good reason for that, and it's kinda tiresome to keep explaining it -- it's not some huge secret or conspiracy or due to horrible customer service. You buy BTC from them via ACH bank transfer. Those typically take 2-3 days to clear
(that's the same for ACH transfers from anyone, anywhere). I think they may tack on another day or two to make sure your ACH bank transfer to them clears without error. They have to do this to mitigate fraud, as they're dealing with exchanging USD via a reversible payment
(ACH transfer) for BTC, an inherently non-reversible payment -- very risky for them.
As for their business model, they make their money off their transaction fees -- and I can imagine ways of handling the transactions so that they would not be exposed to the risks of market swings.