I'm confused as to what you mean. Why do you think that it's just nowadays that people are short on integrity or that everything has become short-term?
Like you I also suspect that people haven't been any different in the past.
But there are two key points I'd like out:
1. I have only seen nowadays,
2. I have met (maybe most?) really smart, able and ambitious people who tend to get little but important details wrong. They view power struggle as zero sum game. They fail to see that to make it you need not only look after your own best interest but of those people around you also. That top is not a singular point, but it is an area of larger structure - a pyramid if you will. And to get to the top of a pyramid you need a strong fundament and if you want to stay at the top you absolutely must hone and take care of your wider base.
Nowadays it's way easier to check the validity of your strategy. It is easier to check historical references for similar contexts as ones own. And these smart people just decide that they will replay the history. And this is the ultimate risk in my opinion - repeating same thing over and over (definition of insanity by Einstein I believe?) and expecting different results. While believing that alternative strategies that are counterintuitive at first are too risky.
