If you take a loan with your first real estate as collateral, you might lose it if you aren’t able to pay the loan. So in the worst case you lose the old and the new property, if you run into cash flow problems.
Taking out a loan to buy a second property can pay for itself, if you do it right and aren’t unlucky. Live in your old house, take out a loan to buy a second house. Rent out the second property and pay the mortgage with that income.
Owning two properties means you have administrative costs and time you need to put in.