That would be true if Uber didn't spend so much money subsidizing rides throughout its history. A customer would be dumb to refuse $2 of service for $1 of payment even if the system being created is going to lock them into an extractive duopoly later.
You can already see this at work as Uber tries to become profitable - ride availability, cost, and quality are getting worse but people continue to use them out of habit or because regional alternatives have been weakened by years of subsidies.
How does Uber doing price dumping (if in fact they were) lock anyone into anything later? Before Uber the options were "walk" or "call a taxi and pray".
The competition ceases to exist and the requirements to re-enter the market once the dumper is a monopoly (usually with the politics power that entails) is beyond the scope for damn near anyone to achieve.
