This is always a good question for any training and development and I guess my response would be then it depends on what it is!
But some development will simply be seen as a cost because you have to do it and may not even see it as personal development. So for example, if you are responsible for health and safety, you may feel a course is not developing you but is more for ticking a box. But if we remain open minded, then I do not believe there is even training like this that we do not learn something from.
There are other areas that are very much a longer term investment. So for example, attending a regular meeting that gives you the skills and tools to develop your business may be seen either way, but I would suggest is more of an investment in a more successful future than a cost to bear.