Certainly you can have failed LEDs!
Lots of people have had overheating problems and ended up with fried LEDs.
If you want fried LEDs you can easily follow in their foot-steps.
1) Box everything up so no air can flow.
2) Have fans that fail unnoticed or are badly placed so there are dead air spaces.
3) Push the current limits on LEDs. So if they are listed as being able to run at 1.5A, run them at 1.5A! That will keep them performing for a nice short time.
4) Also, mount your LEDs on rough warped surfaces. That will keep the stars from being able to conduct their heat into the heat sink so it can be dissipated. This will keep the LEDs extra warm.
5) An easy addition is to leave out the thermal paste. That helps just certain LEDs fry leaving the builder scratching their head as to why only certain ones failed.
6) Lastly don't test anything before powering up your fixture the first time. That helps you over-stress some of the LEDs so they are subtly damaged and hence run considerably hotter than their mates. It quite nicely sets them up for mystifying premature failure.
Sarcasm aside:
When the manufacturer states 50k hours they mean 50k hours. They will likely last far longer than that. If you don't build your fixture in a conservative way with the important details covered then, YES, you can end up with problems in a year - less even! Conversely building your fixture correctly means you will likely dump the fixture for something more efficient, or cooler looking, or brighter, or a different color, lonnnNNNNNNNnnggg before the LEDs start failing.
Do the opposite of everything suggested above and you should be very happy with your results like thousands of others are.
