Even if Arsenal goes to the market and buys a striker worth $100 million, which I believe will not significantly improve their team's performance. It became tiresome watching them consistently make it to the UCL only to drop out early because of their lack of mental toughness. They never learned from their mistakes.. Arsenal was quite balanced last season, but the UCL isn't just about scoring goals.
The market has always offered arteta opportunities. But I thought this wasn't the club's main issue. The winning mentality cannot be purchased. But it must be developed. Arsenal will almost certainly repeat last season's results.
I like your words about mentality, and it is true that mentality cannot be bought because it comes from within the player. However, the players can bring out that mentality if they are very serious about building it, I think that is also what Arteta must pay attention to. He shouldn't just focus on implementing strategy, but he also has to pay attention to small things and as much detail as possible, one of which is mentality. Sometimes we often forget that, because mentality cannot be seen, but we can see it from how they play when they are behind or in a competition that has a lot of pressure.
However, I don't agree if you say that Arsenal doesn't learn from their mistakes, I think they can learn from there. One proof of this is how they can be more consistent this season than last season, I think that is an indicator that they can learn from the mistakes they experienced in the past, it's just that maybe they can be better at correcting them.