Well, if you don't buy it, then you won't build anything for sure. If you have a drawer full of little components, the time may come to actually use it.
Point is: Having the drawers of 'I'll save this just in case!' in all hobbies does in fact come in handy. I find this especially true when some sort of project requires 'yet another adapter' to convert thing a to thing b. Project either goes through or it doesn't, but later on when trying to attack something else, having that little drawer full of weird but useful cables and adapters within living room walking distance sure feels rewarding.