Is it advisable to keep investing in DSP Mutual Fund (Tiger and New Energy) for a long horizon (10–15 years)?

To come straight to the point, it is not advisable to invest in as sectoral fund for such a long period. Three reasons:

1. A multicap fund can give you better returns as the fund manager has the flexibility to take advantage of opportunities across the market.
2. As an investor you are also burdened with the decision on not just whether to continue with the fund, but also whether to continue with the sector itself.
3. One more reason to avoid the sectoral fund is that they tend to have a higher expense ratio.

Lastly invest in direct plan mutual funds with a reliable advisor. Do not fall for free platforms as the hidden costs are much higher.