In a documentary about the film Back to the Future, Michael J. Fox mentions a Woody Allen's joke about traveling in time (also said by the starring character in Woody Allen's film Midnight in Paris), "Don't go back before penicillin."
Practical solutions that in the long term end up meaning a one hundred times bigger problem than the one they'd come to solve: human history. Penicillin is a good example.
What about the future? You don't need a time machine, just a ticket to fly to China for a dose of extreme pollution and overpopulation. By the way, the changes China has experienced lately are a good example that what the alleged “developed” countries sold us as “progress” isn't exactly a good deal after all, is it? Nevertheless, everyone seems determined to hold this fantasy come hell or hight water.
Everybody is very afraid of death, worrying about how many years they will live. Medical care seems to be another everyone's main concern. But nobody seems to even be aware of the unhealthy, miserable conditions under we all live in present world neither shows real interest in changing the habits that cause these conditions.