So depending on the amount of money involved, it can be understandable why they are not accepting trading, provision of crypto services as a genuine prove of funds.
Sounds lame to me, crypto is not just mining, and mining is not for everyone. Stake knows it very well that crypto is a growing industry. Well, their CEO founded primedice too on bitcoin/crypto's earlier years. Many jobs have opened since them due to the growing popularity of cryptocurrency. It's impractical for them to say that most of these crypto jobs are
illegal and only mining is legal, mining is even a business not just a job, and not everyone can open a business especially a crypto related business.
They should update that BS policy of them. It's understandable that they just want to follow some certain regulations but that's too much of BS to consider.