This is really pedantic, but conditionals do imply a specific inverted inference. Specifically in this meme though, the correct inversion is "If the billionaire class is not your enemy, then this budgeting is not relevant to you," which I think we'd both agree with.
The meme only says "if ... then ...". It does not imply the reverse relationship of "if not ... then not ...".
This is really pedantic, but conditionals do imply a specific inverted inference. Specifically in this meme though, the correct inversion is "If the billionaire class is not your enemy, then this budgeting is not relevant to you," which I think we'd both agree with.