Not sure why you're saying the op is not correct. Nothing you said discredits that. The reality is that both are true. There are multiple positive network eff

Not sure why you're saying the op is not correct. Nothing you said discredits that. The reality is that both are true. There are multiple positive network effects at work, as it's evidenced by the growth of these companies. However the barrier to entry is super low, so competition can be quite high. Like you said, just by subsidizing rides/drivers you will start gaining some market share. In the end it's all gonna be about who has the most cash and whose efficiency is the highest. Yeah you could hire a promoter and give out flyers outside a venue, but if you check the data, the ROI is abysmal.