I think falling by the wayside is found in many hobbies, particularly those with a considerable time investment. Many beginners don't appreciate just how long projects like this take.
It is very much the same in another hobby of mine, model engineering (sadly on hold because the college workshop I use is shut due to covid). Many projects start but soon are left on the shelf. As has been said this may be because of life issues or simply that the builder didn't appreciate just what was involved.
The advice given there to beginners is very similar, don't pick a super complex project first up. But interestingly, it is also said don't just pick a project because it is for beginners, you will probably be looking at this for years so pick something which appeals and you want to see finished. If you have your heart set on that major project then go for it but be aware what you are taking on.
Having wanted to take the plunge into wooden ships since I was a child I am now on the point of doing so, it's only taken 50 odd years. I am planning on starting with the De Agostini Victory cross section and, if I get that far possibly moving on to one of Vanguard's fishing vessels. One day I would like to do the Mary Rose having seen it raised and a number of times since, but we shall see.