Some of those who donated to the campaign said they would retract their pledges if Morgan's offer was accepted.
However, a week later, as the deadline for the bids closed, Morgan claimed his conditional offer was a cunning scheme to push up donations.
Listen: Duane Major talks to Newstalk ZB's Chris Lynch
In a blog post, Morgan wrote: "If I'd just said there and then that I'd make up the difference, the crowd would have stopped donating immediately.
"I needed a mechanism whereby the crowd would keep donating - perhaps at an even faster rate, since donations were starting to flag. Hence I came up with the idea that I'd demand in return for my help, access to the sheds on the properties.
"Now remember these sheds will be demolished as soon as the crowd donates the property to DOC - so in effect the crowd would actually lose nothing by giving me the exclusive access to them - it would still have access to the beach and virtually all of the rest of the property.
"My faith in the animal spirits of crowds told me however that this would make them hopping mad and they'd keep donating to spite me."
Campaign organiser Duane Major said this morning of their victory: "We have pulled it off, we have pulled it off.
"At 10.57 last night we delivered a pristine piece of beach and bush into the hands of all New Zealanders to look after and cherish and treasure forever.
"My heart is beating and I've got goosebumps and I'm just so thankful for all those people. What a crazy journey."
Mr Major revealed that the final amount raised by the public was $2,278,171.09. The Government supported the bid with a "modest" contribution.
Mr Major said he always thought the bid would be successful.
"I always thought we could do it. You think about the heartbeat of New Zealanders and you think about the numbers. I did not anticipate the crazy, freakish nature of this campaign but boy is this rewarding. It's satisfying to actually pull it off and to take those ideas and hunches and feelings and to put it into practice."
He said it had left them with a deep down sense of satisfaction. "We've done something very special I believe."
Listen: Gareth Morgan spoke to Newstalk ZB's Larry Williams about his cunning plan
Denim Mchardy, who donated to the cause, said: "I live in Bali but the chance to contribute to such an awesome cause was something I couldn't miss out on.
"So we gathered a few of the Kiwi boys in Bali and we all put some money in. Great cause keep NZ owned by NZ."
MP Paul Foster-Bell congratulated the campaigners, tweeting:
Abel Tasman campaign: Timeline
January 22, 2016 - The "Pristine beach in the heart of the Abel Tasman" project is launched on crowd-fundraising website Givealittle, asking for $2 million to buy the seven hectare private beach in Abel Tasman National Park's Awaroa Inlet.
January 26 - The page has seven pledges worth $6300.
January 27 - Spark pledges $20,000 to the Givealittle campaign, which is now at $250,000 with close to 4500 people donating.
January 31 - More than $600,000 has been pledged by 9273 people.
February 3 - Conservation Minister Maggie Barry confirms that the beach will be added to the Abel Tasman National Park if the online campaign succeeds. More than 11,000 have so far raised $750,000.
February 7 - The Givealittle campaign breaks $1 million, with more than 15,000 pledges. Labour leader Andrew Little says the Government should make it a Waitangi weekend to remember by agreeing to meet the remaining cost of buying the beach.
February 9 - More than $1.3 million has been pledged by over 20,000 donors. Millionaire Gareth Morgan offers to front the remaining money, but his offer comes with conditions. He writes on his blog that he will cover the difference needed, but he wants the section of beach that is currently private to remain that way - for his family.
February 10 - A total of $1,520,982.30 has been pledged by more than 24,000 people and businesses. Gareth Morgan's offer is met with outrage, with some people saying they will retract their pledges. The men behind the Givealittle campaign, Adam Gardner and Duane Major, assure pledgers they do not want Morgan's money.
February 12 - The campaign reaches its $2 million target, with more than 33,200 people and businesses donating.
February 15 - Campaign closes, generating more than $2 million. There are donations from 39,249 people and businesses. The final tally is kept secret. Gareth Morgan claims it was his cunning scheme that helped push up donations.
February 16 - The deadline closes for offers to buy the beach. A spokesman for Conservation Minister Maggie Barry says the Government has not ruled out making a "a modest contribution to the appeal should the need arise," but saysat this stage, no commitment has been made.
February 24 - Campaign is successful. Organiser Duane Major announces that the public fundraising effort was enough to secure the beach, with a total of $2,278,171.09 donated. The Government also supports the bid with a "modest" contribution. Mr Major says the piece of beach and bush was delivered into the hands of all New Zealanders at 10.57pm the night before.
