Agree with traffika — the fundamentals haven't changed, but the margin for error got razor thin. In 2024 you could run a mediocre campaign on push traffic and still break even. In 2026 that same campaign loses money from day one because everyone else optimized while you stayed still.
The biggest shift I see is GEO selection. Most media buyers are still fighting over the same tier 1 countries where CPCs went up 40-60% in two years. Meanwhile, tier 2-3 GEOs (Africa, LATAM, parts of SEA) still have the economics that tier 1 had in 2022 — low competition, cheap traffic, and audiences that actually respond to ads because they're not completely ad-blind yet.
The other thing killing people is tracking laziness. I talk to buyers who still rely on the ad network's built-in stats instead of running their own tracker with proper S2S postback setup. You're literally flying blind — you don't know which zone, which creative, which hour of day is making you money vs. bleeding budget. Without granular data, optimization is just guessing.
My approach for 2026: diversify GEOs aggressively, track every conversion at the zone/sub-source level, and kill campaigns faster. If something isn't at least breakeven by day 3 with decent volume, it's dead — move on.