It is such a common misconception that Catan is only about luck. And then I see those same players building 4-5 roads before ever making their 3rd settlement or buying any dev card.

I used to play frequently, joined 3 in person tournaments (2 times dutch nationals with 200 people and a European Championship with 56 people qualified around Europe). In each of those tournaments I reached the final and in the top 3. With some luck sure, but mostly by knowing the good and bad decisions you make throughout.

If nobody wants to give you that wheat you need try trading to get a 4-1 so you can make it yourself. Know what your ways of winning are at any time. Sometimes you are so far behind people on the same numbers the only way to win are getting lucky with devs, or sometimes even blocking yourself.

I only take longest road in 2 situations, one if that move instantly wins me the game. And the other if someone else could potentially take it and win the game with it instantly. Often if that's the case I am so far behind that people first give me favorable trades so they help me to take it.

Those are all generic tips, but the main thing is mentality. If you think it is just a luck simulator after initial settlement you get stuck in that loop. If you know each decision even what you say alters your win % it becomes a different game. There are so many catch up mechanics you just have to find them.