Nothing is risk-free. There is political risk (it gets outlawed), technological risk (it gets hacked), theft risk (it gets stolen), a comet hits the earth risk etc etc.

Additionally, BlockFi pays 8.6% APY on stablecoins. If you have any BTC, ETH, or LTC, they'll pay interest on those as well. Normally interest is paid in like-kind (e.g. a BTC balance generates BTC interest), but with the Flex option, you could have interest from all balances paid as one token. I chose to have everything paid in GUSD stablecoin, for instance, primarily to make figuring out taxes easier.

BlockFi's interest is a very attractive offer, but the risks you're exposed to aren't very transparent.

What could happen that would impact the exchange rate of this 'Stable coin'? What risks exactly is one taking on for the 8.6% interest?

With crypto if it’s on an exchange then you can lose it. Not your keys and all that jazz.

Never worth the risk unless there is a legal insurance provided by the government which there isn’t.

This would have been a good comment if it hadn't said "risk free".

What's the difference between this an Aave?