Why isn't the 'if blank' condition working in my code?

Store Design
1

Hello
Wondering why this “if blank” doesn’t work?

{%- if product.compare_at_price_max !=blank %}
{{ product.compare_at_price_max | minus: product.price | times:100 | divided_by:product.compare_at_price_max  }}
  {%- endif -%}
2

Any help?