My personality is to pick one thing, and then go all out on it. For instance, if I play Civilization, I might tons of a single unit. Or Settlers I might focus on roads. Often this negatively hurts me. The problem is that I just don't have an intuition for how to handle many different aspects of a game. How do I change my mindset when playing?
7 Wonders is a game that rewards flexibility. Moreso than anything else, the winner will be the one who has identified the key weaknesses in the rest of the players and exploits that.
The problem that many players have is they think "I'll go science" or "I'll go military" or some other strategy. Alternatively, they just pick the juciest looking card every time, with no thought to the ultimate purpose for the card.
Both of these methods are bad. 7 Wonders is a game about optimising your draft options. Sometimes that means forgoing wonder levels. Other times that means forgoing brown resources and other times that means neglecting yellow buildings. In all cases, what you should realise is that while your civ has strengths, your opponents are revealing vital information about their game plans in each and every draft.
In one 7 Wonders game I played I was Rhodes (who are very, very strong). I went a very early military building and then pure science and won. The reason that I did that was that I identified early on that nobody was going science and my neighbours were scared of me going military. They went heavy brown resources and yellow/blue buildings. In another game I didn't get a single science card but picked up early game blue cards (which were being ignored by the board), enough military to get my 18 points and denied my neighbours the use of their marketplaces (which were both pointing away from me) by snagging and preventing key resources for their strategy.
In all cases, realising that the game was not multiplayer solitaire was enough to give me resounding wins. Remember not to fixate on a strategy, rather, fixate on your opponents strategies. You won't be able to counter them all, but you will be able to identify the gaps in demand and exploit them.
Well, the first step to changing your mindset is realizing that your strategy could be improved, which you have already done. One big problem with monolithic strategies is that they can be readily identified and countered by other players. The rock-paper-scissor aspect of Civ units allows opponents to build the perfect counter to your single-unit army. A road-building strategy in Catan can be countered by limiting access to brick and wood.
Don't think about just the potential gain from your strategy, but the potential weaknesses as well. Your monolithic strategy may win if it works, but what will happen if it's derailed? A more balanced strategy allows for more options later in the game, and is not so tightly tied to successes in a particular area of the game. If one aspect doesn't work out, you can always pivot to focusing on something else.
Going all-in on one thing can be a viable strategy sometimes, but ultimately that strategy is just the core of an overall goal. Also, plans never survive contact with the enemy.
For Catan, a road building strategy is good for getting to better settlement spots, cutting off opponents, and expanding. It's not just a road, it helps your other strategies.
For Seven Wonders, you can pick a strategy initially, but if the cards don't support it or you see a neighbor is doing the same strategy, it might be good to change it up. Or focus on resources early so you have building flexibility later.
I've never played Civ, but if your opponent can see your units, shouldn't you be able to see theirs and know when they are trying to counter you? Also, you could take your units to a third opponent instead.