Then it's all about tolerance in your case. You are not accustomed to these temperatures. Also, if you tend to sit at one place, you will feel more cold as blood circulation also becomes slow, i.e. why our extremities are the first to feel cold.
The ads will always have an 'asterisk' and everyone knows that and they even say how 'thermals' are an under-layer. Just like undergarment ads show people without upper clothes, same is true for thermals ads. It won't be much of an ad if the guy would be wearing something on top.
Of course there are better quality thermals available like Heat-tec from Uniqlo as someone pointed above and Columbia and other companies, even cheap Decathlon offerings of mountaineering base layers will be better. But you will still feel cold because this is more about tolerance and what you are used to, in this case.
This reminds me of a funny incident. My roommate from college got his first job in Mumbai. One weekend he and his colleagues planned for a trip to Mahabaleshwar. All the Mumbai folk made him buy a couple of sweatshirts because, according to them, it would be very cold. When he reached there, he was so disappointed and all his colleagues were surprised that he could roam around in his t-shirt and asked for a fan when they were all using sweatshirts and blankets. He couldn't put those sweatshirts to use until he returned to Delhi 5 years later. Most of us northern kids of the 90s, would be in school in 5 degress sitting in nothing but a shirt and a sweater and nowadays winters have become a joke. I never needed a 'razai' after 2006, until I shifted to Himachal in 2014. And again didn't need it here this year because now body has become accustomed to this cold and we have become accustomed to wearing 2-3 layers of light fleece clothing.
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