SpaceX has made no secret of its mobile wireless ambitions. It wants to offer service that rivals any of the big three: AT&T, Verizon Communications, and T-Mobile.

But how? SpaceX doesn't seem to be able to do it with space-based infrastructure alone. Building a wireless spectrum portfolio and terrestrial infrastructure to offer a high-quality national service could take years and cost hundreds of billions of dollars.

SpaceX could just buy an existing company, especially if its space/land hybrid proves to be more efficient than the traditional players.

CEO Elon Musk sat down with Baron Capital's Ron Baron at the 33rd annual Baron Investment Conference in New York on Friday. Starlink came up. Baron is a longtime supporter of Musk and believes Starlink can be a trillion-dollar business.

Starlink is SpaceX's space-based broadband product. Today, it's ideal for fixed-wireless access in rural areas, and serves more than 13 million customers in more than 170 countries using more than 11,000 satellites in low-Earth orbit. Third-quarter Starlink earnings before interest, taxes, depreciation, and amortization (Ebitda) were $3.5 billion, up from $1.9 billion a year ago, on revenue of $5.2 billion, up from $3.1 billion a year ago.

SpaceX has been acquiring wireless spectrum, which is essentially the pipes that carry wireless data. It's an early step in morphing Starlink into a mobile wireless carrier. SpaceX has acquired some 80 megahertz of spectrum. T-Mobile, for instance, has closer to 400 megahertz.

"I think SpaceX will be able to get very far with the spectrum that it's acquired," said Musk on Friday. "But if we're able to make much better use of the spectrum than, say, a legacy telco is, we could just acquire that legacy telco and use that spectrum 10 times more effectively."

Exactly how SpaceX can be 10 times more effective is for network engineers to decide. SpaceX, undoubtedly, believes the latest technology and its space-based assets can improve operations. It didn't respond to a request for comment.

The improvement is almost beside the point. M&A is likely more interesting to investors.

"A major carrier acquisition would simultaneously solve spectrum, [technical issues], roaming, retail/distribution, handset relationships, customer care, device financing and, most importantly, time," wrote Barclays analyst Kannan Venkateshwar on Monday. "That would make buying increasingly attractive if SpaceX's objective really is a large-scale consumer mobile business."

SpaceX would also benefit from depressed valuations -- that it created. Telecom stocks have been affected by SpaceX's mobile ambitions. Coming into the week, shares of AT&T, Verizon, and T-Mobile are down an average of 10% since the end of May, just before SpaceX's record-setting June IPO. Shares of the three trade at an average of about 10 times earnings expected over the coming 12 months, down from about 12 times a year ago.

Venkateshwar called a T-Mobile purchase the "strategically cleanest Big Three combination," adding that it has the lowest rural share, which would mesh nicely with where SpaceX is strong.

Verizon isn't as strategically sound, but a deal could get done. "Verizon is in some ways the sector wild card, given its mature customer position, balance sheet constraints and greater need to find inorganic ways of changing its growth trajectory," Venkateshwar added.

AT&T has valuable assets but the weakest strategic fit.

Buying a carrier might be the easiest, fastest way to achieve Musk's goals. The path is still "convoluted," Venkateshwar said.

The threat to the big three carriers grows along with SpaceX's wireless investments, and "alters the negotiation calculus for AT&T, Verizon, and T-Mobile," he added. "That is the prisoner's dilemma we have highlighted in our prior notes as, individually, each incumbent benefits from monetizing unused network capacity through wholesale but, collectively, they benefit from denying SpaceX terrestrial access."

It only takes one of the prisoners to flip and upend the entire wireless industry.