How many accounts do I need to trade Stocks. Future contracts, Cryptocurrencies, Forex, Etc.?

Without going into the details of every possible way to invest money, the answer is going to depend on which brokers/service providers you do business with. Some brokerages offer accounts that let you invest in multiple types of product, or let you have multiple accounts under a single customer identity with good UI design that makes this feel almost the same thing.

The best bet is to talk to a professional financial advisor. If you have the wherewithal to be investing in so many different vehicles, you will likely need (or at least strongly desire) to have some professionals helping you with taxes, legal issues, etc.

There is no magic number of required brokerage accounts.

You sign up for an account on an as-needed basis and your decision will usually boil down to asking these questions:

• Do I like their interface?
• Do they offer me enough choices?
  • Investment options: stocks, mutual funds, bonds, crypto, etc...
  • Account types: daytrading, Roths, IRAs, 529s, etc...
• Which extended hours exchanges do they support?

One thing you absolutely shouldn't do is invest in the same stock across multiple platforms unless you want your taxes to get really messy, really fast.