Using your reasoning, Microsoft could never have had a monopoly on Windows because you always could have bought a Mac.
You can't define a monopoly as "your competitors aren't popular" because otherwise it'd be illegal to invent new product categories, as at the start you'd be the only player in the new space. You can't define it that way for another reason: it punishes success.
As the sibling comment rightly says, monopolies are acceptable. But, as the EU clearly point out, a greater onus is put on monopolies to avoid abusing their monopoly power.
> Nevertheless, the Commission investigated to what extent competition for end users (downstream), in particular between Apple and Android devices, could indirectly constrain Google's market power for the licensing of Android to device manufacturers (upstream). The Commission found that this competition does not sufficiently constrain Google upstream for a number of reasons, including:
They are not punished for their behavior in the downstream market (in which they barely participate). They are punished for their behavior in the upstream market. We consumers do not participate in the upstream market.
Nevertheless, the EU commission considered whether the lack of a monopoly in the downstream market ameliorated the monopoly effects in the upstream market and found it did not.
There are.other mobile OSes available as well. I'm sure Microsoft will gladly let you use their OS for the right price, KaiOS, Ubuntu phone OS could be resurrected, you could role your own, I'm sure Symbian is for sale somewhere, how about Meego.
If you want to have Google apps on your phone you can't sell any forked android version.
Like, own all cinemas in a country but home-viewing keeps profit low, so now it's fine to only allow people to visit your cinemas if they buy clothes from your clothing company?