C'est donc un coup de chance si tu t'es retrouvé à travailler pour Google.
Here, the fact that the person ended up working for Google is not a hypothetical situation, but the conjunction "si" is used.
How does using "si" in this manner differ in meaning from using "que"?
UPDATE:
I wonder if this « si » sentence structure is used when you want to emphasise the very (one) reason why something happened.
= C'est donc seulement parce que tu as eu un coup de chance que tu t'es retrouvé à travailler pour Google.
If I’m correct in my assumption, does the following sentence sound natural? It uses « si » to desribe an event that has already happened, not a hypothetical situation.
Si je t'en ai parlé, c'est parce que je te fais confiance à 100 %.