When you say lied to someone, that simply means they financed your gambling or gave you money for something which you misappropriated! Sorry am not the type that gambles with people's money because it puts pressure on you and trust me , very few people have managed to flip this into a profit!!!
Anybody that wants to gamble and wants to enjoy their peace of mind, don't gamble with loan money, or money meant for a different purpose, you will thank me later .
You are right, there would be no reason to lie if you gambled with your own money and probably lost it, you owe no one any sort of explanation, after all it's your money. But In a situation where you lost an amount of money that doesn't belong to you gotten from either your friend, loan company, bank and so on, it would be really difficult to just say it straight up that you actually used their money to gamble