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.
In my experience, trading can generate more profit than mining. I have seen lots of people in my stay in the crypto industry gaining millions of dollars in profit from a hundred to thousand dollar investment in just a matter of few months. I believe as long as there is a ledger to prove the fund is coming from trading profit, it should be recognized as a valid source of income. Though in a scenario where the initial trading fund is a huge sum of money, the person holding that fund should also give proof of the source of the initial fund.
@OP, If you have businesses or other investments outside crypto, then maybe you should try using that/those as a prove of fund.
The way I see it, Platinum 4 is a high rank with a high amount of wager requirement. With that amount of money for gambling, it should be pretty easy to prove your source of funds (for most whales) since you are expected to have six+ figures job, legitimate businesses, etc. Without that proof, there are only drug dealers and the like. Trading should be fine though if you have the record, should be treated fairly similar to this:
Sales of shared or other investments / liquidation of investment portfolio / bonds
Source: ToS
Anyway, there's nothing to worry about for small-time gamblers since who cares about the origin of $100? It is only applicable to whales.
I wonder if the quoted statement from the TOS is only applicable to fiat currency.