The difference between me and a level 30 player is that I buy these powerful cards less often than they do, because I see something that they don't about the shape of the board.
Agreed 100% with this. I'd say this represents the difference between level 30s and lower levels as well.
As someone who sometimes flirts with level 30, I feel like I often can generate decent enough engines on engine boards, and get a pretty good feeling for when engine boards or big money boards are going to be dominant. I feel like I tend not to overbuy terminals. There are definitely some boards where I think I see the synergies pretty well, and sometimes even better than the level 40 opponents that I end up facing from time to time.
But there are other times where there are combinations together that I just simply can't fathom just by looking at the board... until it destroys me. I think some of that's experience admittedly.
Case in point where experience is huge: I played a live game yesterday with three other players (the best of whom would probably be Level 10-15) who brought Base Set + Cornucopia, and we had the following in play:
$3 Fortune Teller
$4 Throne Room, Remodel, Farming Village, Tournament
$5 Hunting Party, Market, Horn of Plenty
$6 Fairgrounds, Adventurer
The three other players in the game opened Fortune Teller + something (one of them Farming Village, one of them Tournament, one of them Silver), whereas I opened Remodel/Silver.
And they all just stared at me for grabbing that Silver instead of a Fortune Teller. "Why wouldn't you want the attack card?" the best of the players asks me.
"I'm just not that kind of guy."
And after spending the next couple turns Remodeling Estates into Farming Villages and Tournaments, I get the first Province with no Estates in hand. It dawns on them that the Fortune Teller is forcing me to cycle my deck to put the Province on top to draw with the Tournament, and they spend most of the rest of the game clearing their decks of Curses from Followers.
Second game: same set (they prefer to play that way), nobody buys a Fortune Teller until the very end (for the 15th card with Fairgrounds). The game's a lot closer.
I have to admit that I saw the idea of having Fortune Teller bringing Provinces to the top... because I was on the exact opposite side of that idea about a month ago.
I think there's a lot to be said for the learning curve in this game, and a lot of times, it's hard to see exactly how some of the cards are going to interact with each other... until you've been beaten by it once. Or twice. Or...
It seems to me that the Level 40 player not only visualizes that better, but tends to also have more experience.