Most people think once you get to the top of the mountain, the only way is down.
However that's not true...
Once you climb your mountain and conquer it you find a new mountain to climb.
The same principle applies with exercise and nutrition. Once you achieve your goal you transition to a different milestone. Whether it's getting bigger, leaner, stronger, you shift your mindset and change up your approach in terms of how you will climb that new mountain.
Now of course theirs maintenance which I'm totally for, however, there's always something else to conquer and you want to love what you are doing so you can keep on doing it. Making the process fun and enjoyable is the number one hack for success.
My view on this is if you can find a reason to keep on doing something then you should keep on doing it as long as it's ethical of course.
All in all, find the new mountain to climb, devise a plan, and give yourself enough time to conquer it.