Are all three of these sentences equally fine?

Are these all the same?

1. The more we earn, the less careful we become about money.

2. The more we earn, we become less careful about money.

3. The more we earn, the less careful we are about money.

I am confused about the sentence structures used here. I feel the first one makes sense though.

I hope someone can help me understand the rule behind this!

Solution 1:

In a comment, FumbleFingers wrote:

Your #2 is completely "non-idiomatic", but the other 2 aren't so hot either, even though at least they both include the the more ... the less juxtaposition. The problem is you've switched from a verb with "more" to an adjective with "less", which rather messes up the "parallelism". Better would be to have a verb on both sides of the "equation", as in The more we earn, the less we care about money.