Say we have $e^{e^{e^{e^e}}}$. Since exponents raised to exponents is the same as multiplying them, this is equivalent to $e^{4e}$:
$$e^{e^{e^{e^e}}}=e^{4e}$$
Factoring out an $e^e$:
$$e^{e^{e^e}}=e^4$$
The left side now collapses to $e^{3e}$, leading to the equality $3e=4$.
Clearly my mistake was in the part where I divided both sides by $e^e$, but why am I not able to do this?
It's because $e^{e^{e^{e^e}}}$ isn't $e^{4e}$ in the first place (and neither is $((((e^e)^e)^e)^e)$, which is $e^{e^4}$). The left expression is a power tower, where exponentiation happens right-to-left, not left-to-right as required for the power multiplication rule $(a^b)^c=a^{bc}$.