Some 17 years on, those 200,000 shares he was given are worth about $23m (£17m) - and the 63-year-old says he's ready to start cashing them as soon as he can.
"Every chance I get going forward, I'll sell a little bit more," he tells the BBC.
"The shares have been going up so radically it keeps messing up my life plans - you really can't know the future, so it's better to sell early and in intervals."
Lavoie is far from being the only one who has seen the value of his stake in SpaceX rocket over the years.
The company's founder, Elon Musk, said on Fox News that SpaceX's listing on the stock market in June had likely made "several thousand" employees millionaires - including staff "who were working on the production line".
According to reports, there are estimated to be 4,400 new millionaires created by the listing.
Unlike most newly-listed firms, SpaceX shares are set to be released in stages: the first 20% on 6 August, with more due in batches through the rest of the year.
Whether or not shareholders decide to sell their stake at the first opportunity is a matter for individuals. Unlike Lavoie, some may choose to hold onto their shares altogether in the hope of bigger gains later.
SpaceX listed on the Nasdaq in June, in the biggest initial public offering (IPO) in history, valuing the rocket and satellite firm at more than $2 trillion.
It briefly made Elon Musk the world's first trillionaire, before the stock cooled and his fortune slipped back below the milestone within weeks.
In its first results as a public company this week, the firm's quarterly revenue was shown to have nearly doubled to $7.8bn (£5.8bn) from a year earlier, while its spending ballooned to $18.3bn - more than six times what it was a year ago.
Overall, SpaceX made a net loss of $143m in the three months to June, and a loss of $2bn during the first six months of the year.
Musk pushed back against sceptics on an earnings call: "I think people are really underestimating Starlink". He predicted the satellite internet service - the one part of the company that is currently making a profit - could one day deliver a majority of the world's internet.
But shares in the company tumbled on the back of the earnings report, with investors generally spooked by the huge amounts of money being spent on AI.
Lavoie plans to use his money from selling some of his shares to fund a hotel he is renovating in Pontebba, Italy's northeastern Friuli region, plus a small brewery.
He says is priority for the future is raising awareness of air pollution in the area, in partnership with a local environmental group.
Before he was hired, Lavoie was interviewed by Musk himself.
"He's a very charming person when he wants something," Lavoie says.
He wouldn't be drawn on Musk's politics - "that's his business" - but is unreserved about the company: "I've always been happily supportive and impressed, and would work hard with those incredible people again."
Some analysts value SpaceX at less than half its current stock market price, warning its ties to xAI carry real financial risk - part of a broader worry on Wall Street that sky-high valuations for AI-linked firms, including SpaceX, OpenAI and Anthropic, could prove overdone.
Sinead O'Sullivan, an economist who has previously worked for Nasa, told the BBC in June she thinks SpaceX is an "Elon Musk ego project".
"You're buying a share of the Elon Musk brand more than any kind of space industry," she said.
But Ron Epstein, an aerospace analyst at Bank of America Securities, says the recent share price swings say more about the market than the company.
"A lot of it has to do with macro trends," he says. "None of it really has anything to do with what's going on fundamentally at the company."
He says investors judging SpaceX purely as an AI bet are missing the point: "They're not just a compute provider. They're not just an AI company. It's a far more complicated picture than that."
SpaceX, he adds, has cut the cost of reaching orbit from around $10,000-$20,000 a kilogram to about $2,000 with its Falcon 9 rocket - "they have built a railroad to space."
Lavoie, for his part, isn't rattled. He says: "The solid business model of SpaceX will prove itself to be worth the investment,"even as he takes some of his own winnings off the table.
SpaceX shares sink after first earnings report reveals huge AI spending plans
