Let’s say that you have a constant growth rate of 1mm a month. 5 inches is equal to 127mm and 127mm divided by 12 is equal to 10.6 years of constant P.E. Now all this math is not based on fact, experiences or any data; I have in fact pulled the 1mm number out of my ass because I think it reasonable to gain at least 1mm a month. So to answer your question I think it depends on the person, I probably would not have the patience nor desire to grow 4 inches. I think most would eventually find other hobbies.
Very few people, if any, experience a constant rate of growth for very long. Nearly all experience an initial growth phase of some magnitude and duration, and then hit a plateau at some point. For some that plateau can last months to years. Some never break through a plateau.
Plotting out your “expected growth” in the future based on initial gains is almost certain to lead to disappointment.