Helion's latest funding round was US$425 million, bringing total funding to over a billion, on a US$5 billion valuation. To give that money back to their investors, assuming a 40% profit margin, they'd need to sell something like 100 copies of Orion at US$30 million each, totaling 5 gigawatts. For the investors to consider them successful, it would need to be more like 2000 copies of Orion, totaling 100 gigawatts.
That's a completely plausible market size (although it's not just "all over the country", because the country they're in only has 1161 GW of generation capacity and is barely building any), so their NRE costs to date are not an impossible burden. It really depends on four things:
1. Can they hit such a low price target as US$30 million per 50-megawatt power plant? Can they ship anything for US$30 million a pop?
2. Will they be allowed to sell to China, where the customers are?
3. Will solar energy get cheaper still, forcing them to an even lower price point?
4. Will opex of the resulting reactors be manageable?