The certain destroyer

The biggest problem with all this sage advice is that it is seldom something that can conveniently be shoved on someone else to do. I mean, come on, why can't they give suggestions about how your neighbours or parents or someone else can sort your issues? It is ALWAYS about how your character is the reason and how you should change it for things to go well with you. As though people find it that easy to change character traits.

Tiru falls within the same category of sage advisers. If you asked him, he'd ask you, 'Did you think achieving success was easy?" Ugh!

Azhukkaru udaiyaarkku adhusaalum onnaar vazhukkaayum kedeenpadhu - Tirukkural

If you be filled with envy, it shall destroy you even if your enemies fail to do so - Loose Translation

It is sort of surprising for me, though, to hear that from Tiru. Because envy has a way of creating additional enemies for you and, eventually, they will bring you down. After all, the difference between envy and ambition is that ambition is makes you aspire to achieve what you do not yet have; envy causes you to feel that those who have achieved are less worthy than you if not outright unworthy.

Essentially, your friends can never achieve what you have not yet achieved because the moment they do you'll start envying them and talk ill of them. Which, in effect, means that you can be friends only with those who have achieved lesser than you, never with those who have been more successful.

So, yes, Tiru is right. You get opportunities only from those who can GIVE them to you. Which would mean that those people are likely to be more successful than you. If you are filled with envy, you end up alienating exactly those people who can help your progress. They do not need exactly to hate you or consider you an enemy. It is sufficient for them to see you as not worthy of the opportunities that they may be able to give you.

So, yes, even if enemies who will actively work to destroy you fail to do so, your envy will cause your downfall by alienating you from people and drying up opportunities for success. It is better to learn from success than to merely envy it.