[notaki]

I've heard of market saturation, but market share bubble?

Bloomberg is not making a simple point. The article is titled as if there is, without a doubt, a bubble. When a bubble pops, everyone loses money and only the strongest companies survive. Many new entrants into a rapidly growing market, some of which get shaken out or acquired as the market grows and consolidates, does not constitute a bubble.

Your second paragraph is an argument against this being "an investment bubble".

I agree 100% with the last paragraph.