Completing the FAFSA is optional, however, failure to do so locks one out of pretty much any loan program, grant or scholarship. The processed FAFSA application will spit out something called an "expected family contribution", which is no way reflects what you will actually pay.
I too (nearly) own my on home (only reason I don't pay it off today is for tax purposes), a farm, and a rental (in which my 3 students currently live). I also make a very good wage, though I have enough retirement savings, I could retire today. My 3 college students have nice fat 529s. I am a heterosexual, , white (biological) male, married to a heterosexual white (biological) woman (ok so wife is an eighth Cherokee, but not a tribal member, so we don't ever put that down). I filled out the FAFSA for all three, expecting, like you, not any assistance.
Daughter #1 got a $1,000 grant this semester. One twelfth of total yearly expenses, but it helps. Since she is a history major with an education minor, the state is begging her to accept a teacher scholarship, but she (and I) don't want her at the mercy of the state board of education when she graduates.
Son is a pretty average guy, and I paid full price for him. He's trying to get his grades up and get contracted with ROTC and into the ROTC SMP program which will pretty much cover his college expenses.
Daughter #2, whose life I ruined by making her repeat 2nd grade, has had a 4.0+ GPA ever since, and received an academic merit scholarship which fully paid her tuition this semester (roughly $6K).
To put my savings in perspective, the "savings" amounts to 7 mortgage payments on my students' college townhouse.
So do or do not. You don't know what you will get unless you fill it out.