Interview vs an Invitation to a meet-and-greet

I was offered a phone interview from a big investment company scheduled next week. The recruiter also told me about attending the Meet-and-Greet event which is 2 hours long. However, I don't live in the city where the meet and greet event is taking place :/ so I would have to buy tickets , book a hotel room all could reach 300$ expenses.

My question is, how crucial are those Meet and Greet events? if I don't attend, would it harm my chances of getting the job ? even if i do well in the phone interview?

this is going to be my first official job interview !

if I don't attend, would it harm my chances of getting the job ? even if i do well in the phone interview?

Yes. If someone makes a great impression and meet-and-greet, they're favored.

all could reach 300$ expenses

You'd be broadcasting to your potential employer that you don't want to invest $300 for the chance to meet them and possibly get a job. From their perspective, $300 is peanuts; their department spends that or more on lunch out.

Investment firms pay very well. This is your chance to get their attention and shine. Personally, I would go "all in" and chase the opportunity. But that's your decision. How badly do you want this? How hard have you worked for this so far?