Damon Van Mierlo, 38, was living with his gran in Dronfield after losing his job in Spain, when the 82-year-old noticed £80-£90 missing from her purse, Chesterfield Magistrates Court heard.
Prosecutor Becky Allsop said: "On July 3 she had been away for a week and heard a noise coming from the outhouse - she was concerned and noticed some money was missing.”
She added that Van Mierlo’s grandmother found an empty bottle of vodka and police found her bank card in his possession during his arrest.
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An online banking check revealed £90 had been spent on transactions that she had not made.
Ms Allsop said: “Her grandson came to live with her on May 4 and it was clear he had alcohol and drug addictions.
“At one point when she was away she had left money with a neighbour to drip feed to the defendant in the hope he wouldn’t spend the whole lot at once on drink and drugs.”
The court heard on another occasion Van Mierlo was seen “rifling” through the pensioner’s handbag, claiming to be looking for keys.
Van Mierlo, who has no previous convictions, admitted theft and fraud.
David Gittins, mitigating, said his client had lived an “interesting life”.
He added: “He worked on superyachts - it’s a work hard, play hard lifestyle and when not working you would go out and party hard with colleagues.
“This has led to drink and drug problems which he has had for many years - he openly accepts he took the money and the way he treated his grandmother is wholly unacceptable.
“This was a watershed moment and has made him realise what he was doing.”
A magistrate told Van Mierlow: “Stealing from your granny is not something to be proud of - it was a breach of trust.
“We know you’re remorseful and hope it never happens again.”
Van Mierlo was handed a 12-month community order with 80 hours unpaid work, a 12-month restraining order and 10 rehabilitation activity days.
He was ordered to pay £180 compensation, a £114 victim surcharge and £85 court costs.