Is holding a large cash position while I 'wait for a dip' a good strategy?

It rarely works, and it usually costs money. Waiting for a dip is market timing in disguise: you must correctly guess when the drop will come and then have the nerve to actually buy when everything looks terrible, two hard things most people fail at. Meanwhile, markets rise more often than they fall, so your cash frequently misses gains while you wait, and the 'dip' may arrive only after prices have already climbed past where you started.

Cash sitting idle also loses purchasing power to inflation over time. If you have a lump sum, the evidence favors investing it promptly per your target allocation, or averaging it in over a few months if that helps you sleep. Keep cash for its real jobs, emergency fund and near-term spending, not as a bet against a market you can't predict. Time in the market beats waiting for a perfect entry.