Lindy Effect
The future life expectancy of a non-perishable increases with its age.
Explanation
If something non-perishable has been around for a long time, it will probably continue to exist for a long time. Shakespeare's plays have been performed for 400 years and will likely be performed for another 400. Last year's bestseller probably won't last another decade. Named after Lindy's restaurant in New York where comedians noticed that long-running shows tended to keep running.
Real-World Example
Shakespeare has been read for 400 years—will be read in 2424. This year's bestseller? Probably forgotten by 2030. COBOL (1959) still runs banks. The hot JavaScript framework from last year? Already deprecated. Restaurants open 50 years will likely last; the trendy spot that opened last month, probably not.
How to Apply
For learning: Study things that have lasted (classics over trending). For building: Use proven technologies for critical systems, experiment with new ones for non-critical. For investing: Companies profitable for decades > hot startups. Rule of thumb: Its future life expectancy = its current age. The older, the bolder.