"The grass is always greener on the other side "
Make sure you do the best you can do and accept the results.
Not two businesses, two owners or two future owners are the same. There are many ways to run a business, the only thing that never changes is that everything always changes!
To the selling owners: disconnect from the business and enjoy your life after it! To the future business owners: take advantage of the strong points of the business you just acquired and don't start changing everything from the start (than you'd be better of starting a business from scratch!).
You can only buy or sell a certain business once at a given time: comparing with other businesses and other times doesn't make sense.
Again, make sure you've given it all and than e satisfied with the results.
“Success is not final, failure is not fatal; it's the courage to continue that counts.”