My favorite example is the Roomba. Cool new vacuum cleaner invented, ridiculously broad/abstract patents filed... result, near zero progress for 20 years.

Patents don't give you rights to a product. Only a certain implementation of one.

Your competitors will patent improved versions if you don't. They might also invent a product using a new implementation leaving you with no market.

And in practice, it doesn't work that way. Companies acquire patents on each minor upgrade to their technology.

Your competitors won't exist if your basic patents are broad enough to deny them access to the market.

I was thinking more along the lines of competitors who are in the same space as you (let's say, light bulb manufactures) -- you patent a new type of bulb, your competitors could patent a bunch of improvements on it to deny you future market on improved versions.