Acting Justice Brian Martin told Robert Peter Matthewson, 36, that he was a danger to the public and the prospect of reoffending was high.

Matthewson, of Mangana, was found guilty by a jury of three counts of unlawfully setting fire to vegetation in the Fingal Valley on December 8, December 18 and December 30, 2019.

The court heard he was angry with the owner of the remote Mangana bush block he was trying to buy.

During sentencing, Acting Justice Martin said "at no time have you accepted responsibility for what you have done".

"That's because I didn't do it," Matthewson interjected.

He said that Mathewson tried to mislead police by saying that he "f***ing hated fire".

"That was a false statement," he said.

"You continue to deny responsibility as you just did to me then and in February 2021 you tried to flee the jurisdiction and I have no doubt that was because of consciousness of guilt."

In sentencing submissions, Crown prosecutor John Ransom and defence counsel Fran McCracken stated that no other comparable crime had been considered by the Supreme Court of Tasmania.

"It is unlike anything else this court has seen," Ms McCracken said.

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Acting Justice Martin said Matthewson had no diagnosable mental disorder but there were features of his background that attracted a degree of sympathy.

He highlighted a large number of prior offences for setting fire to houses, cars and hedges. He had involvement in 18 fires between the ages of 11 and 18 years. There were five prior convictions for arson.

"The last of these firelighting offences was in 2003," he said.

"These offences were not due to a fascination with fire but because you wanted others to suffer as you had suffered."

Matthewson was in a state of highly charged emotion because the off-grid dream he wanted to create, he dubbed Bluestonia, was unlikely to succeed because of the falling out with the landowner.

"What you were hoping to achieve is not clear, I cannot be sure whether you wanted to cause damage for revenge or whether the owner might relent or whether you gave way to emotions and vented your anger," he said.

"It's also possible something in your mental state played a role."

"You saw fire as a means and raises the possibility that you wanted Zac Mead [the landowner] to suffer."

Acting Justice Martin said it was pure good fortune that the loss of life was prevented.

"Not satisfied with one or two fires you lit a third on December 30 on the most dangerous of days," he said.

Temperatures were close to 40 degrees and winds 50km/h on that day.

"In addition, you added an accelerant to make sure the fire took hold," he said.

"You should be under no illusions about the huge risk to lives and the wider community you created."

Acting Justice Martin said that after the December 18 fire Matthewson was found heavily intoxicated at his residence.

"You claimed that a burn mark on your arm was because you had not showered since September," he said.

"I reject that explanation and in my view police were correct that it was a burn mark."

The court heard that the December 30 fire caused $30 million damage to timber industry assets and that fighting the fire cost Tasmanian Fire Service $3.7 million and involved up to 150 firefighters.

The total area of the fire was 22,275 hectares.

Matthewson was also sentenced for two counts of aggravated assault in October last year when he called triple zero and told police he had a firearm and intended to shoot people.

In a police interview, he said he wanted to die at the hands of police by forcing them to shoot him.

"I know it's selfish but I'm too gutless to do it myself," he said.

The court heard comments on passing sentence in 2003 when Justice Peter Underwood remarked that wherever Mathewson went fires appeared.

Acting Justice Martin set a non-parole period of four years and six months.