I wouldn't think that way at all, I've had this disease for 39 years, had surgery 16 years ago. Our life expectancy with Crohn's is no different than the normal population.
If you're thinking of the risk of colon cancer, though it is slightly higher than the general population (3-5 percent on average), long as you're under the care of your GI, getting the regular tests and check ups, I wouldn't worry about
that either.
Think of it as being at 1/4.