Having your money in a money market account instead of a regular savings account is pretty safe and can make you more money than just having the money in a regular savings account with a regular bank.
But when you put money into a money market account it's considered as an investment of your money and not considered as a regular deposit.
So unlike with a regular savings account your money is not insured through the FDIC like the savings account or checking account would be.
I have a money market account and so far after 10 years I've never lost any money in the money market account and hope I never do.
But it is possible to lose money in the money market account if the market conditions change or the interest rates drop.
So keep an eye on the market conditions and interest rates and economy and if you notice that you might lose money in the money market account you can withdraw your money from the money market account and transfer the money to a regular savings account or checking account.