Idiom for quality tools not making up for lack of ability

Solution 1:

"All the gear, no idea" conveys someone who has spent lots on equipment but doesn't have the knowledge/ability to actually get the best out of it (or even necessarily get anything out of it).

For your film example it might work as:

That wannabe film director has all the gear but no idea! I can't believe he spent £20k on that movie camera when the plot and actors are so bad that he's have to pay any cinema to screen it!

As an aside, there is also a related idiom "A bad workman blames his tools" which comes at this situation from the other direction: the result is poor and it's because the person didn't have the ability, but rather than admit that he claims that his tools weren't good enough.