it seems if one makes more than $154K a year, then one is not allowed to contribute to his/her Roth IRA account for the year? though one is still allowed to contribute to the traditional IRA account, right?
The gist of your understanding is correct, but your numbers seem outdated. The actual number(s) are determined based on YOUR USA Federal tax filing status. Additionally, deductibility of Traditional IRA contributions and/or Required Minimum Distribution requirements need to be factored to engineer a strategy. And remember, contributions to a traditional and/or a Roth IRA, are made with EARNED INCOME. Out of the box, CAPITAL GAINS are NOT EARNED INCOME.
I think I can get away with contributing money to the Traditional IRA account. I might have overcontributed to the Roth IRA account. on the form 1040, one puts capital gain on the line 7, and summed together with other incomes. I think it's considered as one of the earned incomes.
I found a calculator created by Fidelity that estimates the amount that one can contribute to his IRA account if his income is greater than $154,000; one can contribute to the maximum amount, but it's not tax-deductible. IRA Contribution Calculator - Fidelity