High risk is not a judgment on the seller. It is a portfolio classification: the entire segment is bracketed by the history of disputes, refunds, and complaints it produces, and the cost of processing rises along with it.
Falling into this bracket changes three things at once. The rate gets higher, the rolling reserve increases, and the tolerance for chargeback rate shrinks. Generalist gateways tend to simply decline the account instead of pricing the risk.
In practice, operating in high risk demands what any serious operation should already have: an honest sales page, fast delivery, support that responds, and a visible refund policy. The difference is that here this stops being good practice and becomes a condition for continuing to process.