Gun’s financial problem. Please explain

Han Shangyan is the owner of K&K worldwide. In the novel, the company spreads to many countries including Taiwan and USA, not just Norway and China. The Chinese branch is the weakest and is losing money. I get that. 

In the drama HSY is the owner of a successful company. His personal funds are not little. His aunt also sends money into his account to buy the necklace. So after he gives the necklace to Tong Nian, he has to give aunt her money back and pay for the necklace himself. I understand the necklace is worth 900 000¥. 

Again, his personal funds are not little, and yes I get the story happens in a short space of time. Still, How is it that he, the owner of a successful global business, is in personal financial difficulty in the drama?

It helps a little. I know he's not the only investor. That guy, Navi, is his business partner. However, your personal funds and business funds are usually separate.

He didn't have this huge problem in the novel (it was more minor), but I suspect the whole "draw it out and explain that he's broke" storyline in the drama is all to explain the scene at the end when Squiddy wanted to give him all her savings, and he felt so touched. That scene was important because it showed that she was unconditionally (and stupidly as he noted) into him.

It just seems like a big plot hole to me. I loved the drama anyway lol. Loved it to bits and wanted more fluff in and extended 2 or 3 episodes.