One caution about your open policy, since you are wondering whether generosity is backfiring: it is not causing the disputes, but it does interact badly with one specific case.
A no-questions refund on a digital product that has already been downloaded is worth thinking about, not because most people abuse it, but because the small number who do will keep coming back and there is nothing on your side stopping them. That is a different problem from disputes, and it wants a different remedy - usually a time window rather than a refusal, which is much easier to state and much easier to enforce.
What I would keep from your current approach: fast, generous, and no argument. That is genuinely correct and it is worth more than the money it costs, because the alternative is disputes, which cost more.
What I would add:
- A stated window rather than an unbounded one
- The policy visible before purchase, so it does work for you at the point where people are deciding whether to trust you
- A record of who you have refunded, so a repeat pattern is visible
And track the reason codes on the disputes you do get. If most say fraudulent rather than product not as described, the descriptor answer above is your problem and the policy is not, which changes what you should spend the next week on.