Real brokers provide liquidity, transparency and of course timely withdrawals. There is no excuse for delaying the withdrawal because client funds are supposed to be segregated.
Scammers don't segregate funds, and may have already spent your investment the moment it was sent. When choosing a broker ask for proof of segregated funds.
For example with a good broker, usually in the back office there's a break down of assets with diversification held across many different large banks to ensure safety.