To get the top management interested in ISO 27001, you need to show them the business benefits of implementing this standard. There are 4 potential benefits:
1) Compliance - e.g., getting a certificate if this is what a client requires, and by doing this keeping this client.
2) Marketing edge - e.g., if your company has an ISO 27001 certificate and your competitors do not, you might get new clients and new revenue because of it.
3) Lowering the expenses - since ISO 27001 is very helpful in preventing incidents, you will also reduce potential costs that would happen if an incident occurs.
4) Improving internal organization - ISO 27001 requires you to define roles, responsibilities, and processes more precisely, therefore forcing you to think through how to organize your company.