Allow me to offer a dissenting opinion here. I agree with your point that many people don't change much, but I don't think that necessarily equates to a lost friendship being a lost cause. Here's my significant experience with the matter.
As I progressed through high school, college, and 6 career towns, I made and lost many friends along the way. Most of the friendships died when I moved away, and though I tried to stay in touch, I found others too lazy or uncaring to do so. After so many years of one-way effort, I eventually gave up on them.
As retirement age approached, I became more sentimental about my past life and relationships. Clinging onto good memories and wanting to rekindle old friendships, I sought out several past, lost friends. They all had families and I don't, so it's understandable that I needed and missed them more than they did me. Thus, I had to swallow my pride, reach out, and be willing to give without expecting much back. And so I did - with emails, calls, and personal visits.
After 30+ years of no contact, I reengaged with 10 past friends that I now stay in touch with regularly. It's not fair that I'm the one who always has to lead the effort, but their friendship makes it worthwhile. Four have become good, close friends again that I visit yearly. We enjoy reminiscing about the past, sharing outdoor activities, and making new good memories.
I think those of us who crave more relationships in life need to reject the fairness rule, striving to be a giver rather than a taker. So what if we have to give 80% to get 20% back? If that 20% is good, then I'd suggest that it's worth the price paid. And throughout this process, we givers become a blessing to others more than we'll ever know.