Cracks are beginning to appear in the fusion energy financing boom.

This happens in every emerging industry. Founders and investors push toward a common goal until the money starts rolling in and their shared vision begins to diverge.

Cracks are appearing in the world of fusion power, which I witnessed firsthand at The Economist’s Fusion Fest in London last week. The overall upward momentum has not abated, with convergence startups raising $1.6 billion over the past 12 months. But people had different opinions on two key questions. When should a convergence startup go public? And does a side job get in the way?

Going public was on everyone’s mind. In the past four months, TAE Technologies and General Fusion have announced plans to merge with publicly traded companies. Both are set to receive hundreds of millions of dollars to sustain their R&D efforts, and some investors have kept faith for two decades and finally see an opportunity to cash in.

Not everyone agrees. Most people I spoke with were concerned that these companies were going public too early and that they had not achieved key milestones that many consider important in judging the progress of a convergence company.

First, to recap, TAE announced its merger with Trump Media & Technology Group in December. Although the deal is not yet complete, the fusion business has already received $200 million of a potential $300 million in cash from the deal, giving it runway to continue with its power plant plans. (The remaining amount will reportedly be deposited into your bank account upon submitting Form S-4 to the U.S. Securities and Exchange Commission.)

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

Both companies have access to cash.

Before the merger announcement, General Fusion was having trouble raising funds, and around this time last year, CEO Greg Twinney posted an open letter appealing for investment and laid off 25% of his employees. It got a brief reprieve last August when investors threw it a $22 million lifeline, but that kind of money doesn’t last long in the world of nuclear fusion, where equipment, experiments and staff costs aren’t cheap.

TAE’s position was not that serious, but it still needed some funding. Before the merger, the company raised nearly $2 billion, which sounds like a lot, but keep in mind that the company is almost 30 years old. Moreover, its pre-merger valuation was $2 billion, according to PitchBook. Investors are at best breaking even.

Neither company achieved scientific break-even. This is a major milestone showing that the reactor design has power plant potential. Many observers doubt it can achieve that goal before other private startups. One executive told me that if they were in that position, they weren’t sure how they would fill the time in their quarterly earnings reports if the company didn’t hit scientific breakeven soon.

If TAE or General Fusion failed to perform, some feared that public markets would hurt the entire fusion industry.

Now, not all is lost. TAE has already begun marketing other products, including power electronics and cancer radiotherapy. This may provide the company with short-term profits to appease shareholders. However, General Fusion has not disclosed any such plans.

And there’s another divide there. Nuclear fusion companies are divided over whether to pursue profits now or wait until the plants are operational.

Some companies are seeing an opportunity to make money in the process. Not a bad strategy! Fusion is a long game, so why not up your odds? Commonwealth Fusion Systems and Tokamak Energy both said they would sell the magnets. TAE and Shine Technologies are both engaged in nuclear medicine.

Other startups worry that side hustles could get in the way. Inertia Enterprises, for example, said it is laser-focused on power plants. This is consistent with what another investor told me a few months ago. — They worried that convergence startups could become distracted by profitable but tangential businesses and fall from the lead.

There is no agreement on the appropriate time to make it public. I’ve heard a few suggested milestones. Some believe startups must first reach the scientific break-even point, where the fusion reaction produces more energy than needed for ignition. No startup has achieved this yet. Other possibilities are facility breakeven (if the reactor produces more energy than the entire site needs to operate) and commercial viability if the reactor produces enough electrons to sell meaningful quantities to the grid.

We may get an answer to that question soon. Commonwealth Fusion Systems expects to reach scientific breakeven within the next year, and some believe the company could use that as an opportunity to go public.