certain business rely heavily on search engine optimization. Take for example you have a PIZZA STORE. Now it is very less likely that anybody would log into search engine for "pizza stores in uk". They would rather search newspaper, tv ads, radio ads to search relevant services. In this scenerio, even if your site gets penalized on search engines it will have no impact on your business
You may wonder how much effect it can have on business earnings, trust me. When you have multi-million dollar business depending on SEO only, thats a big problem.
It depends on what SEO you implement. If you are to manipulate the rankings...That's not a good idea... Build natural way no fooling around....
As more sites sell your product, your rankings will invariably go down (unless somehow you are better at SEO than all the rest). It's a fact of life (perhaps not of SEO), but there is only so much room on the top of the hill. So, that being said, better have a fallback plan.
hiring people and then more people because the business is good just based on SEO is always somewhat of a gamble. what do i do? i probably rip my hairs, bang my head on the computer desk for a while, and then go fishing...