Suggestion for Database Finalization

Hi
I am looking for advice and suggestion for database selection for an application i am developing

First of all i m confused about which database to use
my application has several functions and features

its esports + onling gaming + gaming social media + community( groups , pages, audio rooms)

it has money transactions ( in and out ) + virtual currency + wallets + as well

I selected mongo db but i am confused after more research.
I dont know my data is relational or non relational

Factors to Consider

1. Concurrency ( 100 k Users) . 2 Fast data load ( read / write ) 3. Low server cost ( I am going to use VPS under $ 50/Month). No budget for cloud.

DB selections are

1. MySQl, 2. MongoDB, 3. Postgres, 4. Neo4j 5. Cassandra 6 ArangoDB