It is a fact that your size and prominence can make it more likely that you’ll be sued, and who has the best story is a factor in jury trials certainly, but that’s not the only factor in play and it depends on what kind of case and jurisdiction, etc. In the UK, for example, patent cases are heard before a specialist patent judge and the loser often has to pay the winner’s costs, which restricts vexatious litigation - different kettle of fish entirely. Also cease-and-desist letters can and do go to all and sundry, and you can get your game shut down relatively easily and cheaply under the DMCA etc in some cases.
“Use Micro transactions in your game you owe JP Morgan a licensing fee” - that’s the kind of thing people like to say but the claim is not as brief as the use of micro transactions per se. The claim includes this portion, for example: “wherein the microtransaction includes a first set of attributes and the non-microtransaction includes a second set of attributes, the first set of attributes different from the second set of attributes, and the first set of attributes including a decreased ability to challenge charges as being incorrect when compared to the second set of attributes.”
Quite what that means in layman’s terms I couldn’t tell you without looking at the patent as a whole, and I can’t be bothered right now, but if you don’t do what that thing says, you won’t infringe. So it doesn’t cover JUST using micro-transactions. But you’d be well-advised to consider it before implementing your own system…
Digital IP is a bit of a mess. I’m not sure quite what you’re suggesting but due diligence (especially regarding brands) is a thing to get right before you launch, not after. Also some things like patents and - to an extent - designs can’t be obtained after you’ve disclosed them (sold/trailed/publicised/etc).