Can Shopify support high traffic sites? Is there a risk to pass on Shopify if you have a site that makes several million visits per month?

What is a high traffic e-commerce site?
The largest E-commerce sites in France, excluding Amazon, achieve a maximum of 20 million visitors / month . This is huge, but the attendance figures drop rapidly as soon as you go down a little in the ranking. Private sale, for example, has only 13 million unique visitors (source Médiamétrie//Netratings October 2019).

To manage this traffic, the technical infrastructures are colossal. Numerous servers, help from the cloud, load balancer… we can cite dozens or even hundreds of technical solutions to help manage this traffic. So one can legitimately wonder if Shopify or Shopify Plus can handle such high traffic.
What are the biggest Shopify sites in the world?
Shopify operates over a million e-commerce sites worldwide. All sites are hosted by Shopify on the same platform which appears to be Google Cloud based.
Indeed, Shopify provides little technical information on the management of its infrastructure. But hosting a million sites is already a feat. Imagine that if each site receives only one visitor per month, we are already at more than a million visitors.
Some figures on Shopify to realize the volume
Even if we lack technical data, we can realize the infrastructure of Shopify through their financial communications. Shopify is indeed listed on the New York Stock Exchange and therefore has many transparency obligations.
We learn that the 2018 turnover of all Shopify sites was more than 41 billion dollars ( source ). If Shopify were a single e-commerce site, it would be 20 times bigger than Cdiscount.
For comparison, the total of e-commerce in France in 2019 was 100 billion euros. Shopify, still if it were a single e-commerce site, would represent 40% of total French e-commerce.

I think these numbers speak for themselves about the size and strength of Shopify. Every second shopify collects on average more than 1300 € of payments on its platform, whether it is Shopify Payments or the others. Few platforms in the world can claim to do the same.
Shopify is therefore a solution that can collect a lot of traffic. No doubt about it!