He graduated from an Ivy League college, but was 30 and unemployed when he killed his father.
A New York jury convicted Thomas Gilbert Jr. in shocking murder case.
The younger Gilbert shot his father, Thomas Gilbert Sr., in the head in 2015.
Prosecutors say the reasoning was his father cut his allowance from $1,000 a week to $300 just a few hours before.
His attorneys argued insanity but the jury disagreed.
He will be sentenced in August and could get life in prison on the murder charge.
The 34-year-old’s attorneys plan to appeal.