I asked both companies for the names of big winners. Sabrina Macias, head of corporate communications for DraftKings, suggested David Gomes, a 2014 big winner; it’s him celebrating in the DraftKings ad. When I asked for more names, Macias said, “We have had 20 winners of $1 million prizes.” She promised to get back to me with a list of those names, and never did.

Emily Bass, public relations manager for FanDuel, suggested Scott Hanson, “Scott H.,” a 2014 big winner. When I asked for more names, Bass said her company has “a huge number” of big winners. She promised to get back to me with a list of names, and never did.

Naturally, many who win lawfully at gambling would prefer their identities not be disseminated. State lotteries and some casinos prove that prizes were distributed by issuing audited financial statements, such as this one. As long as the auditors do a good job, players know that purses were paid and shills weren’t hired to leap up and scream, “I won!”

As privately held start-ups in a business area that is unregulated, DraftKings and FanDuel are under no obligation to substantiate their numbers. “We do not disclose financials; that is company policy,” Mohammed Dieye, a DraftKings official, told me. FanDuel says it paid $560 million in prizes in 2014 — click “press kit.” But the statement is a promotional claim, not an auditor’s attestation.

Thus neither company offers anything, beyond its say-so, backing up the advertising. What about the experiences of David Gomes and Scott Hanson?

Gomes, 25, grew up in Boston, is studying to be a physician assistant, and reports that he wisely saved the after-tax portion of his $1 million prize. His big payday came last season, from selecting New England’s Jonas Gray for a fantasy team days before the undrafted free agent ran for a surprising 201 yards and four touchdowns against Indianapolis.

“Sure there was luck involved, but this wasn’t just a wild guess,” Gomes said. “Gray caught my eye in training camp, and the Colts were weak against the rush in 2014. So it was a calculated risk. With state lotteries, a machine issues a number — how do you know if other numbers really won? With online fantasy sports, yes it’s gambling, but you watch the games and know for sure whether your choices were good or not. This is more honest to the public than lotteries based on random numbers.”