I looked at ticket prices recently and honestly it's gotten a bit insane, but it's more nuanced than just "inflation + scammers". Platform fees are definitely monstrous (sometimes 30-40% of the ticket price), but there's also the fact that buzz-worthy artists like Stromae demand way higher fees because the demand is there. Promoters know they're gonna fill the venue so they jack up the base prices. It's not really that it exploded everywhere either - small local concerts stay reasonable, but anything that's a popular artist? Yeah, it's gotten aggressive.
As for cheaper periods, honestly it's complicated. Generally the first tickets put on sale are a bit cheaper, then prices go up as it starts to fill. Sometimes there are off-peak releases or pre-sales for subscribers, worth checking. But if something's doing well and it's a star right now, you can't really count on prices dropping. What really changes things is the platform - shop around directly with several (Ticketmaster, Ticketswap, etc) because fees vary wildly from one to the other. Sometimes you save a decent amount by going through a reseller instead of the official one, even if it's less reassuring.