It happens in every emerging industry: founders and investors push toward a common goal, until the money starts to roll in and that shared vision begins to diverge.

Cracks are emerging in the fusion power world, which I saw firsthand at The Economist’s Fusion Fest in London last week. It didn’t dampen the overall buoyant mood, lifted by fusion startups’ fundraising haul of $1.6 billion in the last 12 months. But people had differing opinions on two key questions: When should fusion startups go public? And are side businesses a distraction?

Going public was at the top of everyone’s minds. In the last four months, TAE Technologies and General Fusion have announced plans to merge with publicly traded companies. Both stand to receive hundreds of millions of dollars to keep their R&D efforts alive, and investors, some of whom have kept the faith for 20 years, finally see an opportunity to cash out.

Not everyone is in agreement. Most of those who I spoke to were worried these companies were going public far too early and that they hadn’t achieved key milestones that many view as vital in judging the progress of a fusion company.

First, a recap: TAE announced its merger with Trump Media & Technology Group in December. Though the deal isn’t yet completed, the fusion side of the business has already received $200 million of a potential $300 million in cash from the deal, giving it some runway to continue planning its power plant. (The remainder will reportedly land in its bank account once it files the S-4 form with the U.S. Securities and Exchange Commission.)

General Fusion said in January that it would go public via a reverse merger with a special purpose acquisition company. The deal could net the company $335 million and value the combined entity at $1 billion. 

Both companies could use the cash.

Before the merger announcement, General Fusion was struggling to raise funds, and around this time last year it laid off 25% of its staff as CEO Greg Twinney posted a public letter pleading for investment. It received a brief reprieve in August when investors threw it a $22 million lifeline, but that sort of money doesn’t last long in the fusion world, where equipment, experiments, and employees don’t come cheap.

TAE’s position wasn’t quite as dire, but it still required some funds. Pre-merger, the company raised nearly $2 billion, which sounds like a lot, but keep in mind the company is nearly 30 years old. What’s more, its valuation pre-merger was $2 billion, according to PitchBook. Investors were breaking even at best.

Neither company has hit scientific breakeven, a key milestone that shows a reactor design has power plant potential. Many observers doubt they’ll hit that mark before other privately held startups do. One executive told me, if they were in those shoes, they’re not sure how they would fill time on quarterly earnings calls if the companies didn’t hit scientific breakeven soon.

If TAE or General Fusion doesn’t deliver results, several people feared the public markets would sour on the entire fusion industry.

Now, not all may be lost. TAE has already started marketing other products, including power electronics and radiation therapy for cancer. That could give the company some near-term revenue to placate shareholders. General Fusion, though, hasn’t revealed any such plans.

And therein lies another divide: fusion companies remain split on whether they should pursue revenue now or wait until they have a working power plant.

Some companies are embracing the opportunity to make money along the way. Not a bad strategy! Fusion is a long game, so why not improve your odds? Both Commonwealth Fusion Systems and Tokamak Energy have said they’ll be selling magnets. TAE and Shine Technologies are both in nuclear medicine.

Other startups are worried that side hustles could become a distraction. Inertia Enterprises, for example, told me that they’re laser-focused on their power plant. That jibes with what another investor told me months ago: — they were worried that fusion startups could get distracted by profitable, but tangential businesses and fall off the lead. 

There wasn’t consensus on the right time to go public either. I heard a few proposed milestones. Some believe startups should first reach that scientific breakeven milestone, in which a fusion reaction generates more energy than it needs to ignite. No startup has achieved that yet. The other possibilities are facility breakeven — when the reactor makes more energy than the entire site needs to operate — and commercial viability — when a reactor makes enough electrons to sell a meaningful amount to the grid.

We may have an answer to that question sooner than later. Commonwealth Fusion Systems expects it will hit scientific breakeven sometime next year, and some think the company might use that as an opportunity to go public.