In my experience, if you take care of them, wearing them once a week and washing in the machine once a week, they can easily last three years (still good after that, only less nice). So you would use them at the rythm of 7 each 3 years. 140*3/7 = 60 years.
Now of course, you probably have t-shirts of various sizes. Either you will fatten or get slimer, and be able to wear them all, or you may have your children and your wife wear some of them, but that should still be good for 20 years.
Now, you just have to find a startup that would print pants instead of t-shirts, and another with shoes, and and you'll be entirely clothed for life! :-)
Edit: In this case, it wasn't a failed startup (though the company did eventually fail), it was the marketing department picking a name for our new product, and printing up 500 t-shirts and a truckload of other sales collateral for a trade show, without bothering to check if the name was already trademarked (which it was, by another software company, in the same city).