Raymond Smith, 68, died during the home invasion in the tiny town of Greenbushes, about 240km south of Perth, in December 2023.
He was reported missing in the days after the murderous assault and his body was found by police in a nearby rural property about a month later.
James Terence Hunt, 33, was found guilty of Mr Smith's murder, and Paul Douglas May, 43, guilty of his manslaughter following a Supreme Court trial that finished earlier in June.
Hunt was sentenced on Friday to life imprisonment, with a non-parole period of 21 years.
May, a boilermaker and father of two, was sentenced to 17 years, with parole eligibility after 15 years.
"The taking of another human life is always a terrible thing," Justice Amanda Forrester said.
Mr Smith, who lived alone, was targeted by Hunt, May and a third man, Kevin Allan Craig Potter, for his belongings and the marijuana that he grew at his home.
The trio were methylamphetamine users and hatched their plan during a drug-fuelled bender.
Potter, who was previously sentenced to life behind bars with a minimum period of 15 years for murder, betrayed his mate Mr Smith.
The older man had generously allowed Potter to stay at his home when he had nowhere else to go.
On the day of the killing, Potter went to visit Mr Smith at his home early in the morning.
Mr Smith was making Potter a coffee when Hunt and May burst through the back door with beanies covering their faces.
Mr Smith grabbed a baseball bat and said "who the f*** are you?", Justice Forrester said.
The men dragged Mr Smith by his hair to the bathroom, where he was forced onto the floor and tied up with cling wrap and beaten on the legs with the bat as he struggled.
Hunt, a roof plumber-turned-shearer, then stomped on his chest with severe force three times, ultimately killing him.
"Mr Smith didn't make a sound after that and was lifeless," Justice Forrester said.
The men ransacked his house before fleeing.
Hunt, also a father of two children, later said "I think I killed the old (man)", the court heard.
Mr Smith's body was later moved to a nearby bush property.
"You did all this selfishly, motivated by greed and a desire to feed your methamphetamine habits," Justice Forrester said.
Mr Smith's daughter, Bronwyn Smith, told the court he was a loving dad and grandfather, who liked to help people.
"Dad was a trusting, kind person, always kind to animals and people," she said while reading her victim impact statement.
"He was knowledgeable, generous and always offered to assist people in need."
She said she suffered "an eternal pit of despair" imagining her father's final moments.
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