You can lose money on an investment you never touch.
Some brokers charge a custody fee for keeping your shares.
Some charge a fixed account fee, every month.
Some charge you for doing nothing: an inactivity fee.
Moving to another broker can cost a fee per holding.
And in Italy, a 0.2% tax on what you hold comes every year.
EU firms must send you a yearly costs report. Have you read your last one?
Education, not investment advice.