Is this genuine Arbitrage opportunity or is there something I am missing

I have a query on what seems like a insane Arbitrage opportunity for a retail/individual investor to earn Fixed income. I want to take views and inputs on this whether I am missing something or it is a genuine arbitrage.

If someone is in India and invests say 1 million $ in US 30 year bond with yield of 5%+ currently, combined with currency depreciation, they will get nominal returns of at least 9% on the investment every year assuming 4% currency depreciation of Indian Rupees against USD.

This seems like a good opportunity and insane arbitrage to get 9% Fixed returns for next 30 years. Is there something wrong with this.

Additionally, on maturity, the principal will appreciate in INR terms as well at at least 3.5 to 4% every year over 30 years, so it might have more than doubled in INR terms over the period of 30 years.

Below are the only possible downsides i can see, along with probability of it happening

1) The USD can depreciate in INR - Impossible , if history is to go by, long term USD wins against INR by minimum 3.5 to 4% average. Structurally the country India does not have anything that can make global investors to flock to India to strengthen Indian Currency. So long term, USD appreciating vs. INR has 99.99% probability

2) The US can go bankrupt - This seems like the only downside, that US can go bankrupt and dishonor the treasury bills. Though it has not happened before, it can be a 5% possibility event over span of 30 years, but still its worth the risk.

3) Taxation, yes Tax will be paid anywhere from 30 to 39% on the bond coupon in Indian Tax system, but that tax is there on any income. So all things being equal, tax won't be a differentiator between this and other income sources.

4) Curbs on foreign investors either from US or India - This can be a unfortunate event where either of the government could curb investments in such instruments and restrict outflow from India. Might happen in future but currently no such policy

5) US currency can be replaced - This seems like the only downside, if USD no longer holds any value and is replaced by some other standard currency. I am not sure how anyone can get around this.

6) Interest rates can rise beyond current 5% - Yes, this can bring down the bond trade value, but maybe the person can reinvest the coupon received in the new higher rate bonds to partially offset any potential loss of higher interest payments.

Assuming the person investing in this is more interested in fixed income rather than growth and will not intend to sell the bond till maturity, this seems like a good opportunity.

Is there anything I am overlooking in this. Thanks for your views.