Besides, ideas grow and take on a life of their own as you work on them. By the time your interpretation of the idea takes shape it's going to be distinctly different from the original idea that inspired you.

The only way to keep people from stealing your ideas is by never talking to anybody about them. That's surely the worst of all options.

You can literally try to clone any YC company after demo day. All the startups get covered on techcrunch making their ideas public. Just pick the one you like best and open your favorite editor. They only got a 6 months head start, so what's stopping you?

Not quite true. A growing number are hardware/robotics or biotech or some other field that require significant capital investment and highly specialist Phd-level expertise to even get a proof-of-concept off the ground, so you can't just "open your favorite editor" and get started.

Then you have those which cover a niche that again requires some kind of insider knowledge or connections (it helped for example that Facebook was created in Harvard). That's not to say these are impossible barriers, but again they're not broken by hacking away at node or PHP.

The pool of ideas that a) you, personally, can execute on today and b) have a hope of generating profit or funding within a reasonable timeframe is not as big as people like to think. Much of the low-hanging fruit of profitable ideas that can be executed by the single coder in the proverbial basement has been picked long ago.

As I say, there's not many ideas that seem inspiring, and as you rightly point out, I'm committed to my own foolish ideas.

Have you ever actually done this? If so what was the result? Did you then spend the several years of hard work it typically takes to make a great idea into a successful idea?

What people mean when they say ideas are worth nothing is that a good idea is worth nothing without execution, and the effort required to execute and develop it is usually 1000x that to have the initial idea.