Why does there need to be a 'next'? I've tried cheaper competitors and they aren't even close to how well Roomba's work. As long as they keep building the best

Why does there need to be a 'next'? I've tried cheaper competitors and they aren't even close to how well Roomba's work. As long as they keep building the best quality robots, I'll keep buying them. If they divert resources to a new market and forget about their main product (kind of like Apple has with Mac), I have no issues in buying a competitors product if it's better.